Support using OIDC to authenticate provider

[tcaddy]

Is your feature request related to a problem? Please describe.
I don't like that I have to provide an API key or a set of OAuth credentials in order to auth the terraform provider. I'd like to be able to auth in a manner that doesn't require using secrets (which could be used elsewhere to gain access to Tailscale's API).

Describe the solution you'd like
I would like you to support OIDC authentication for the Tailscale provider.

Additional context
The terraform providers for GCP and Azure AD both support auth'ing with OIDC and it's really nice b/c

1. no secrets are involved
2. there are no long lived credentials used
3. there is no need to reset an Oauth client every 30/60/90/etc days
4. it's more secure

[casperbiering]

Just found that it's already reported here: tailscale/tailscale#13087

[tcaddy]

Oof, sorry to make a dupe issue. I searched for "OIDC" before posting this. That dupe issue is from another git repo so I think maybe this one should stay open since the change would happen in this repo, right?