[11.x] Replace string class names with ::class constants

[panakour]

Replace string class names with ::class constants to be consistent with the rest of the codebase.

This change:

• Improves type safety
• Makes refactoring easier
• Maintains consistency with Laravel's coding style

[SanderMuller]

@taylorotwell I think this is a breaking change on the old route namespacing eg

Route::namespace('Admin') ->group(function (): void { Route::view('dashboard', 'admin.dashboard'); }); 

this now throws Invalid route action: [App\Http\Controllers\Admin\Illuminate\Routing\ViewController]. because the namespace in this PR was changed from \Illuminate\Routing\ViewController to Illuminate\Routing\ViewController I think.

[GrahamCampbell]

The important difference is the leading slash is not included in the ::class name.

[joshmanders]

The important difference is the leading slash is not included in the ::class name.

That's interesting, wouldn't it make sense to prefix with \ when calling ::class internally to make sure it's the fully qualified class name?

[shaedrich]

@joshmanders I had the same idea:
#54185 (comment)

[SanderMuller]

The important difference is the leading slash is not included in the ::class name.

That's interesting, wouldn't it make sense to prefix with \ when calling ::class internally to make sure it's the fully qualified class name?

Made an attempt to reintroduce it via #54189