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>

extensions/lock/extend.php

@@ -35,12 +35,15 @@ return [
     (new Extend\Notification())
         ->type(DiscussionLockedBlueprint::class, BasicDiscussionSerializer::class, ['alert']),
 
+    (new Extend\Model(Discussion::class))
+        ->cast('is_locked', 'bool'),
+
     (new Extend\ApiSerializer(DiscussionSerializer::class))
         ->attribute('isLocked', function (DiscussionSerializer $serializer, Discussion $discussion) {
-            return (bool) $discussion->is_locked;
+            return $discussion->is_locked;
         })
         ->attribute('canLock', function (DiscussionSerializer $serializer, Discussion $discussion) {
-            return (bool) $serializer->getActor()->can('lock', $discussion);
+            return $serializer->getActor()->can('lock', $discussion);
         }),
 
     (new Extend\Post())