feat: add api key credential as client library authorization type

[ldetmer]

Add new ApiKeyCredentials that will pass the appropriate api-key header for authorizing api requests from client libraries

Note: ApiKeyCredentials extends from the base Credential class as Api Keys are not considered oauth2 credentials since there is no access token which is required by GoogleCredentials/OAuth2Credentials. This also follows definition of oauth2 credentials as specified by Google Identity Protocols that require an access token when using Oauth 2.0 to access google APIs.

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[lqiu96]

I think the changes LGTM. I'll need to double check the authenticationType being "" and the refresh() behavior.

[ldetmer]

I think the changes LGTM. I'll need to double check the authenticationType being "" and the refresh() behavior.

FYI, Blake and I discussed refresh with Carl and he agreed no op was correct.

[lqiu96]

I think the changes LGTM. I'll need to double check the authenticationType being "" and the refresh() behavior.

FYI, Blake and I discussed refresh with Carl and he agreed no op was correct.

Yep. I think it makes sense just wanted to confirm the behavior and I think it works as intended. I'll ask about the authenticationType with the Auth Team and once I get their input on this, I think we should be good to go.

[burkedavison]

LGTM

[lqiu96]

LGTM.

@zhumin8 for approval as well

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
93.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud