Improvements to the AssertStatusToAssertMethodRector

[peterfox]

Changes

• Uses PHPStan to a better effect instead of looking at what constants might be used
• Corrects a previously incorrect test
• Adds stubs for Laravel and Symfony responses
• Simplify the docs a little for the rule

Why

I wrote this rule over a year or so ago now and learnt a lot since then. This should now allow for any integer value PHPStan can detect. For example:

-$this->get('/')->assertStatus(400 + 4);
+$this->get('/')->assertNotFound();

Before this the rule would only detect specific constants or the scalar integer using only what the PHP Parser had found.