PLT-2258 Unified login screen and related APIs (#2820)

* Unified login screen and related APIs

* Refactored login API call to be less convoluted

* Removed LDAP login prompt from invite process

* Fixed existing LDAP users being able to log in if LDAP was configured, but disabled

* Gofmt

* Future proofed login API

* Updated login APIs based on feedback

* Added additional auditing to login API

* Actually removed loginById

i18n/es.json

@@ -1560,7 +1560,7 @@
     "translation": "Revocando sessionId=%v para el userId=%v vuelve a iniciar la sesión el el mismo dispositivo"
   },
   {
-    "id": "api.user.login_by_email.sign_in.app_error",
+    "id": "api.user.login.use_auth_service.app_error",
     "translation": "Por favor inicia sesión usando {{.AuthService}}"
   },
   {