idtoken: support providing custom certificate URLs

[keyslapperdev]

The current documentation for Google Chat bot verification shows

All bearer tokens sent with requests from Google chat will have [email protected] as the issuee, with the audience field specifying the target bot's project number from the Google API Console. For example, if the request is for a bot with the project number 1234567890, then the audience is 1234567890.

In their code examples they show that the url to get the keys for validation should be https://www.googleapis.com/service_accounts/v1/metadata/x509/ + ${theAboveIsuee}

As of now this repo doesn't support the kind of JWT validation specified in the docs.

I feel a solution would be to create a module, or extend current functionality, to validate JWT provided a url.

[codyoss]

Thanks for the feature request!

[dennbagas]

Is there any update about this feature?

[codyoss]

Closing in favor of linked issue.