fix auth renew panic

[hghaf099]

Addresses #17013

When handleAuthRenew is invoked, b.AuthRenew is called with nil framework.FieldData here. This request goes to pathLoginRenew and this causes a panic for the case of Okta engine which expects to get a nonce from the field data.
The proposed fix assumes that there could be other code paths that call pathLoginRenew.

2022-11-17T09:30:58.576-0800 [INFO]  http: panic serving 127.0.0.1:61385: runtime error: invalid memory address or nil pointer dereference
goroutine 830 [running]:
net/http.(*conn).serve.func1()
        /Users/hamid/.go/src/net/http/server.go:1850 +0xbf
panic({0x59d6c80, 0x9f71ec0})
        /Users/hamid/.go/src/runtime/panic.go:890 +0x262
github.com/hashicorp/vault/sdk/framework.(*FieldData).Get(0x0, {0x658e728, 0x5})
        /Users/hamid/repo/vault/sdk/framework/field_data.go:61 +0x27
github.com/hashicorp/vault/builtin/credential/okta.(*backend).pathLoginRenew(0xc000d1bf50, {0x7109638, 0xc001c5fb60}, 0xc001599500, 0x0)
        /Users/hamid/repo/vault/builtin/credential/okta/path_login.go:147 +0x246
github.com/hashicorp/vault/sdk/framework.(*Backend).handleAuthRenew(0x55bbaa0?, {0x7109638?, 0xc001c5fb60?}, 0x0?)
        /Users/hamid/repo/vault/sdk/framework/backend.go:620 +0xe5
github.com/hashicorp/vault/sdk/framework.(*Backend).handleRevokeRenew(0x0?, {0x7109638?, 0xc001c5fb60?}, 0x106bdf6?)
        /Users/hamid/repo/vault/sdk/framework/backend.go:561 +0x4e
github.com/hashicorp/vault/sdk/framework.(*Backend).HandleRequest(0xc001694000, {0x7109638, 0xc001c5fb60}, 0xc001599500)
        /Users/hamid/repo/vault/sdk/framework/backend.go:198 +0xe7
github.com/hashicorp/vault/builtin/plugin/v5.(*backend).HandleRequest(0xc000dc8780, {0x7109638, 0xc001c5fb60}, 0xc001599500)
        /Users/hamid/repo/vault/builtin/plugin/v5/backend.go:92 +0xce
github.com/hashicorp/vault/vault.(*Router).routeCommon(0xc0001c8af0, {0x7109638, 0xc001c5fb60}, 0xc001599500, 0x0)
        /Users/hamid/repo/vault/vault/router.go:764 +0x160b
github.com/hashicorp/vault/vault.(*Router).Route(...)
        /Users/hamid/repo/vault/vault/router.go:544
github.com/hashicorp/vault/vault.(*ExpirationManager).renewAuthEntry(0xc00001ab40, {0x7109638, 0xc001c5ec60}, 0xc001599200, 0xc000352b60, 0x34630b8a000)
        /Users/hamid/repo/vault/vault/expiration.go:1978 +0x36e
github.com/hashicorp/vault/vault.(*ExpirationManager).RenewToken(0xc00001ab40, {0x7109638, 0xc001c5ec60}, 0xc001a22420?, 0xc001c38b00, 0x659a2be?)
        /Users/hamid/repo/vault/vault/expiration.go:1352 +0x5ad
github.com/hashicorp/vault/vault.(*TokenStore).handleRenew(0xc0005f4780, {0x7109638, 0xc001c5ec60}, 0x9?, 0x18?)
        /Users/hamid/repo/vault/vault/token_store.go:3471 +0x2e5
github.com/hashicorp/vault/vault.(*TokenStore).handleUpdateRenewAccessor(0x0?, {0x7109638, 0xc001c5ec60}, 0x0?, 0xffffffffffffffff?)
        /Users/hamid/repo/vault/vault/token_store.go:2531 +0x33f
github.com/hashicorp/vault/sdk/framework.(*Backend).HandleRequest(0xc000cbb420, {0x7109638, 0xc001c5ec60}, 0xc001599200)
        /Users/hamid/repo/vault/sdk/framework/backend.go:291 +0xa82
github.com/hashicorp/vault/vault.(*Router).routeCommon(0xc0001c8af0, {0x7109638, 0xc001c5ec60}, 0xc001599200, 0x0)
        /Users/hamid/repo/vault/vault/router.go:764 +0x160b
github.com/hashicorp/vault/vault.(*Router).Route(...)
        /Users/hamid/repo/vault/vault/router.go:544
github.com/hashicorp/vault/vault.(*Core).doRouting(0xc00129c000?, {0x7109638?, 0xc001c5ec60?}, 0xc001c5e810?)
        /Users/hamid/repo/vault/vault/request_handling.go:817 +0x2c
github.com/hashicorp/vault/vault.(*Core).handleRequest(0xc00129c000, {0x7109638, 0xc001c5ec60}, 0xc001599200)
        /Users/hamid/repo/vault/vault/request_handling.go:1008 +0x11da
github.com/hashicorp/vault/vault.(*Core).handleCancelableRequest(0xc00129c000, {0x7109638, 0xc001c5e8d0}, 0xc001599200)
        /Users/hamid/repo/vault/vault/request_handling.go:665 +0x1545
github.com/hashicorp/vault/vault.(*Core).switchedLockHandleRequest(0xc00129c000, {0x7109638, 0xc001c5e2a0}, 0xc001599200, 0x80?)
        /Users/hamid/repo/vault/vault/request_handling.go:472 +0x539
github.com/hashicorp/vault/vault.(*Core).HandleRequest(...)
        /Users/hamid/repo/vault/vault/request_handling.go:433
github.com/hashicorp/vault/http.request(0x5f53c80?, {0x70f81e0, 0xc001c5e1b0}, 0xc000345600, 0xc001599200?)
        /Users/hamid/repo/vault/http/handler.go:910 +0x86
github.com/hashicorp/vault/http.handleLogicalInternal.func1({0x70f81e0, 0xc001c5e1b0}, 0xc000345600)
        /Users/hamid/repo/vault/http/logical.go:354 +0xb6
net/http.HandlerFunc.ServeHTTP(0xc001651595?, {0x70f81e0?, 0xc001c5e1b0?}, 0xc001325d40?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
github.com/hashicorp/vault/http.handleRequestForwarding.func1({0x70f81e0, 0xc001c5e1b0}, 0xc000345600)
        /Users/hamid/repo/vault/http/handler.go:835 +0x39d
net/http.HandlerFunc.ServeHTTP(0xc00188f398?, {0x70f81e0?, 0xc001c5e1b0?}, 0x0?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
net/http.(*ServeMux).ServeHTTP(0xe?, {0x70f81e0, 0xc001c5e1b0}, 0xc000345600)
        /Users/hamid/.go/src/net/http/server.go:2487 +0x149
github.com/hashicorp/vault/http.wrapHelpHandler.func1({0x70f81e0, 0xc001c5e1b0}, 0xc000345600)
        /Users/hamid/repo/vault/http/help.go:25 +0x129
net/http.HandlerFunc.ServeHTTP(0xc0006d9280?, {0x70f81e0?, 0xc001c5e1b0?}, 0x2559440?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
github.com/hashicorp/vault/http.wrapCORSHandler.func1({0x70f81e0?, 0xc001c5e1b0?}, 0xc00188f510?)
        /Users/hamid/repo/vault/http/cors.go:29 +0x1e5
net/http.HandlerFunc.ServeHTTP(0xc00129c000?, {0x70f81e0?, 0xc001c5e1b0?}, 0xc000a295c0?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
github.com/hashicorp/vault/http.rateLimitQuotaWrapping.func1({0x70f81e0, 0xc001c5e1b0}, 0xc000345600)
        /Users/hamid/repo/vault/http/util.go:110 +0xc30
net/http.HandlerFunc.ServeHTTP(0xc001c5e120?, {0x70f81e0?, 0xc001c5e1b0?}, 0xc001a20110?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
github.com/hashicorp/vault/http.wrapGenericHandler.func1({0x7106b20?, 0xc000350a80}, 0xc000345300)
        /Users/hamid/repo/vault/http/handler.go:422 +0xdb3
net/http.HandlerFunc.ServeHTTP(0xc001651595?, {0x7106b20?, 0xc000350a80?}, 0x9fdb060?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
github.com/hashicorp/go-cleanhttp.PrintablePathCheckHandler.func1({0x7106b20, 0xc000350a80}, 0xc000345300)
        /Users/hamid/go/pkg/mod/github.com/hashicorp/go-cleanhttp@v0.5.2/handlers.go:42 +0x93
net/http.HandlerFunc.ServeHTTP(0x0?, {0x7106b20?, 0xc000350a80?}, 0x1317a74?)
        /Users/hamid/.go/src/net/http/server.go:2109 +0x2f
net/http.serverHandler.ServeHTTP({0x70f0690?}, {0x7106b20, 0xc000350a80}, 0xc000345300)
        /Users/hamid/.go/src/net/http/server.go:2947 +0x30c
net/http.(*conn).serve(0xc001a89400, {0x7109638, 0xc000cf42a0})
        /Users/hamid/.go/src/net/http/server.go:1991 +0x607
created by net/http.(*Server).Serve
        /Users/hamid/.go/src/net/http/server.go:3102 +0x4db

[ccapurso]

Looks good to me