MM-27688-OpenId Connect (#16222)

* implement openid connect

* update error strings

* handle OpenIdSetting.Secret as FAKE SETTING

* add openid to telemetry

* update config defaults, add telemetry

* fix bug with Office365

* Retrieve Office365 AuthData from IdToken

* fix linter

* add feature flag, reset defaults for config

* fix build error

* fix unit tests

* add authentication permission to Feature
Flags

* turn off feature flag

* set default button color

* set default button color only on openid

* fix for merging FeatureFlags in config

* remove feature flag

* revert config changes

* remove debug statements

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/user.go

@@ -1691,11 +1691,12 @@ func login(c *Context, w http.ResponseWriter, r *http.Request) {
 		enableUsername := *config.EmailSettings.EnableSignInWithUsername
 		enableEmail := *config.EmailSettings.EnableSignInWithEmail
 		samlEnabled := *config.SamlSettings.Enable
-		gitlabEnabled := *config.GetSSOService("gitlab").Enable
-		googleEnabled := *config.GetSSOService("google").Enable
+		gitlabEnabled := *config.GitLabSettings.Enable
+		openidEnabled := *config.OpenIdSettings.Enable
+		googleEnabled := *config.GoogleSettings.Enable
 		office365Enabled := *config.Office365Settings.Enable
 
-		if samlEnabled || gitlabEnabled || googleEnabled || office365Enabled {
+		if samlEnabled || gitlabEnabled || googleEnabled || office365Enabled || openidEnabled {
 			c.Err = model.NewAppError("login", "api.user.login.invalid_credentials_sso", nil, "", http.StatusUnauthorized)
 			return
 		}