Configuration: Add ability to customize okta login button name and icon (#44079) (#45483)

* add ability to customize okta login button name and icon

* update configs, add basic frontend test

* add icon to oauth settings type

* trigger tests

* fix typecheck

(cherry picked from commit 51cd6f3cc5)

pkg/api/login.go

@@ -93,7 +93,10 @@ func (hs *HTTPServer) LoginView(c *models.ReqContext) {
 	enabledOAuths := make(map[string]interface{})
 	providers := hs.SocialService.GetOAuthInfoProviders()
 	for key, oauth := range providers {
-		enabledOAuths[key] = map[string]string{"name": oauth.Name}
+		enabledOAuths[key] = map[string]string{
+			"name": oauth.Name,
+			"icon": oauth.Icon,
+		}
 	}
 
 	viewData.Settings["oauth"] = enabledOAuths