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

tests/unit/Install/Prerequisite/WritablePathsTest.php

@@ -41,7 +41,7 @@ class WritablePathsTest extends TestCase
 
         $problems = $writable->problems();
         $this->assertCount(1, $problems);
-        $this->assertRegExp(
+        $this->assertMatchesRegularExpression(
             "%^The .+/tests/fixtures/writable_paths/missing directory doesn't exist$%",
             $problems[0]['message']
         );
@@ -59,7 +59,7 @@ class WritablePathsTest extends TestCase
 
         $problems = $writable->problems();
         $this->assertCount(1, $problems);
-        $this->assertRegExp(
+        $this->assertMatchesRegularExpression(
             "%^The .+/tests/fixtures/writable_paths/missing directory doesn't exist$%",
             $problems[0]['message']
         );