fix: FeatureTestTrait::withRoutes() may throw all sorts of errors on invalid HTTP methods

[paulbalandan]

Description
Per documentation, withRoutes() accepts a list of 3 to 4 element arrays where the first element is the HTTP verb (or the special add to mean all verbs). However, there's no validation for invalid methods and is just directly called upon RouteCollection which may result in unknown method, TypeError for parameter, etc.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[paulbalandan]

Installing ImageMagick on PHP 8.4 is taking too long. 🤔