An exported TSImportEqualsDeclaration should be wrapped in an ExportNamedDeclaration instead of having .isExport = true

[bradzacher]

Code from #4129

namespace Bar {
  export const bar = 123;
}

export namespace Foo {
  export import TheBar = Bar;
}

I didn't know that export import was even valid at all in TS.
Right now this will emit a TSImportEqualsDeclaration with .isExported = true.
This is wrong because it means that rules have to have special handling specifically for this case in order to understand TheBar is exported.

We should breaking change fix the AST here so that the AST is instead ExportNamedDeclaration > TSImportEqualsDeclaration to align with everything else.

[JoshuaKGoldberg]

Resolved because #5885 was merged into v6. This'll be released with the v6 version.