MM-26410/MM-26825 Improve syncing between favorites category and preferences (#15048)

* MM-26410 Allow moving channels into Favorites when they're favorited in prefs

* MM-26410 Fix management of Favorites category when updating preferences

* MM-26410 Add management of Favorites category when deleting preferences

* Address feedback 1

* Remove WHERE (1=1) from query

* Remove unnecessary sq.Expr

* Rewrite query to use left join

* Remove redundant where statement and add some more tests

* Fix linting issues

* Rename addChannelToFavoritesCategory to addChannelToFavoritesCategory

i18n/en.json

@@ -1814,6 +1814,10 @@
     "id": "api.preference.delete_preferences.delete.app_error",
     "translation": "Unable to delete user preferences."
   },
+  {
+    "id": "api.preference.delete_preferences.update_sidebar.app_error",
+    "translation": "Unable to update sidebar to match deleted preferences"
+  },
   {
     "id": "api.preference.preferences_category.get.app_error",
     "translation": "Unable to get user preferences."
@@ -1822,6 +1826,10 @@
     "id": "api.preference.update_preferences.set.app_error",
     "translation": "Unable to set user preferences."
   },
+  {
+    "id": "api.preference.update_preferences.update_sidebar.app_error",
+    "translation": "Unable to update sidebar to match updated preferences"
+  },
   {
     "id": "api.push_notification.disabled.app_error",
     "translation": "Push Notifications are disabled on this server."