Generating ID token with ImpersonatedCredentials does not support overriding quota project

[lzy-2022]

Is your feature request related to a problem? Please describe. ImpersonatedCredentials accepts a quota project in its builder, and the quota project is properly overridden when generating an access token. However, when generating id token with the idTokenWithAudience() method, it won't perform such override. The impact is that if a service does impersonate many IdTokens on its own quota - it exceeds a default limit of 60k.

Describe the solution you'd like It seems to me that providing the quota project in the additionalFields argument when invoking the IamUtils.getIdToken() method would work

Describe alternatives you've considered There doesn't seem to be good alternatives.

[TimurSadykov]

@sai-sunder-s what do you think?