Laravel components v8 (#2576)

- update actions ci
- include json for 4 spaces tab
- provide output int for process code exit
- adhere to parent type hint of builder
- mailer instance now needs a name, multiple can be instantiated
- getOriginal now uses mutators in the model
- Temporarily loosen MailableInterface requirements. This avoids an immediate BC break for classes in extensions that implement this interface.
- Temporarily provide (and autoload) old symfony translator interface
- make queue exception handler compatible with the contract of L8
- Update phpunit schema for newer version
- Update phpunit assert calls for newer version

src/Discussion/UserState.php

@@ -91,7 +91,7 @@ class UserState extends AbstractModel
      * @param Builder $query
      * @return Builder
      */
-    protected function setKeysForSaveQuery(Builder $query)
+    protected function setKeysForSaveQuery($query)
     {
         $query->where('discussion_id', $this->discussion_id)
               ->where('user_id', $this->user_id);