Add support for additional where* methods to route groups

[ollieread]

This PR addresses the change originally mentioned in #43509 and reverted in #43523.

Unlike the original PR, it adds support for all of the additional where* methods available on a route, to a route group, by adding the CreatesRegularExpressionRouteConstraints trait.

It works directly on the router, handled by Router::__call with an explicit check for beginning with where, that proxies to the method. There is no check to see if the method exists, because if it does not, it will be passed to the RouteRegistrar::attributes method automatically, so will achieve the same without the requirement for an additional condition.

Route::whereIn(['foo', 'bar'], ['one', 'two'])->prefix('/{foo}/{bar}')->group(function () {});

And on a RouteRegistrar, using the trait.

Route::prefix('/{foo}/{bar}')->whereIn(['foo', 'bar'], ['one', 'two'])->group(function () {});

This PR also adds 8 tests that test both of the approaches, as they are slightly different. No changes have been made to RouteRegistrar::allowedAttributes because the trait turns them into where attributes.

[morloderex]

@ollieread Have you tested this with route caching enabled?

[ollieread]

@ollieread Have you tested this with route caching enabled?

I have not, but I'm confident that I do not need to. Route groups already support where attributes, and these methods are wrappers for the where attribute. There is nothing new created because of this, it's just easier.