Ability to fully customize the oidc discovery url

Actually, it's not possible to use a custom url (as https://host/.well-known/oauth-authorization-server by example) because the path /.well-known/openid-configuration is already add.

https://github.com/hashicorp/vault-plugin-auth-jwt/blob/175b36bab10d932d581b01db8e94dd78bd23a49e/vendor/github.com/coreos/go-oidc/oidc.go#L97

Is it possible to make this configuration more flexible?

Thanks

Start by reading vendor/github.com/coreos/go-oidc/oidc.go around line 97 and trace the plugin's OIDC configuration path. Define how a fully custom discovery URL should be configured, then verify that a URL such as https://host/.well-known/oauth-authorization-server is used without appending /.well-known/openid-configuration.

Written by the indexing model from the issue text.