chore(phpstan): enable phpstan in bundled extensions (#3667)

* feat(phpstan): pick up extended model relations typings
* feat(phpstan): pick up extended model date attributes
* feat(core): introduce `castAttribute` extender
Stops using `dates` as it's deprecated in laravel 8
* feat(phpstan): pick up extended model attributes through casts
* fix: extenders not resolved when declared namespace
* fix(phpstan): new model attributes are always nullable
* chore(phpstan): add helpful cache clearing command
* Apply fixes from StyleCI
* chore: improve extend files provider logic
* chore: rename `castAttribute` to just `cast`
* chore: update phpstan package to detect `cast` method
* chore: enable phpstan in bundled extensions
* chore: rebasing conflicts
* chore: rebasing conflicts
* chore: typings for latest 1.7 changes

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

framework/core/src/Extend/Validator.php

@@ -31,7 +31,7 @@ class Validator implements ExtenderInterface
      * Configure the validator. This is often used to adjust validation rules, but can be
      * used to make other changes to the validator as well.
      *
-     * @param callable $callback
+     * @param callable|class-string $callback
      *
      * The callback can be a closure or invokable class, and should accept:
      * - \Flarum\Foundation\AbstractValidator $flarumValidator: The Flarum validator wrapper

framework/core/src/Extension/Extension.php

@@ -236,7 +236,7 @@ class Extension implements Arrayable
     }
 
     /**
-     * @return string
+     * @return string|null
      */
     public function getVersion()
     {

framework/core/src/Notification/Blueprint/BlueprintInterface.php

@@ -36,7 +36,7 @@ interface BlueprintInterface
     /**
      * Get the data to be stored in the notification.
      *
-     * @return array|null
+     * @return mixed
      */
     public function getData();
 

framework/core/src/Notification/MailableInterface.php

@@ -16,7 +16,7 @@ interface MailableInterface
     /**
      * Get the name of the view to construct a notification email with.
      *
-     * @return string
+     * @return string|array
      */
     public function getEmailView();
 

framework/core/src/Post/Event/Posted.php

@@ -9,25 +9,26 @@
 
 namespace Flarum\Post\Event;
 
-use Flarum\Post\Post;
+use Flarum\Post\CommentPost;
 use Flarum\User\User;
 
 class Posted
 {
     /**
-     * @var \Flarum\Post\Post
+     * @var CommentPost
      */
     public $post;
 
     /**
-     * @var User
+     * @var User|null
      */
     public $actor;
 
     /**
-     * @param \Flarum\Post\Post $post
+     * @param CommentPost $post
+     * @param User|null $actor
      */
-    public function __construct(Post $post, User $actor = null)
+    public function __construct(CommentPost $post, User $actor = null)
     {
         $this->post = $post;
         $this->actor = $actor;