[8.x] Add new Stringable::test method

[ryangjchandler]

This pull request introduces a new Stringable::test method that checks whether the string matches a particular pattern, but doesn't return the match(es).

This is essentially just a shortcut for $stringable->match('//')->isNotEmpty() but something that I do often enough, and also macro, that it warranted a pull request to the core.

[ryangjchandler]

I realise now that matches might get confused with matchAll, perhaps another good method name would be test, just like JavaScript's method.

[taylorotwell]

Yeah, maybe test would be good since that is what JavaScript calls it.

[ryangjchandler]

@taylorotwell All done. 🤟

[foremtehan]

Can we have it on Illuminate\Support\Str too?