authorize: support authenticating with idp tokens (#5484)

* identity: add support for verifying access and identity tokens

* allow overriding with policy option

* authenticate: add verify endpoints

* wip

* implement session creation

* add verify test

* implement idp token login

* fix tests

* add pr permission

* make session ids route-specific

* rename method

* add test

* add access token test

* test for newUserFromIDPClaims

* more tests

* make the session id per-idp

* use type for

* add test

* remove nil checks

pkg/identity/oauth/github/github.go

@@ -256,3 +256,13 @@ func (p *Provider) SignIn(w http.ResponseWriter, r *http.Request, state string)
 func (p *Provider) SignOut(_ http.ResponseWriter, _ *http.Request, _, _, _ string) error {
 	return oidc.ErrSignoutNotImplemented
 }
+
+// VerifyAccessToken verifies an access token.
+func (p *Provider) VerifyAccessToken(_ context.Context, _ string) (claims map[string]any, err error) {
+	return nil, identity.ErrVerifyAccessTokenNotSupported
+}
+
+// VerifyIdentityToken verifies an identity token.
+func (p *Provider) VerifyIdentityToken(_ context.Context, _ string) (claims map[string]any, err error) {
+	return nil, identity.ErrVerifyIdentityTokenNotSupported
+}