Simpify Request::is() and Request::fullUrlIs()

[sebdesign]

#39857 replaced a foreach loop with a Collection::contains(), but the Str::is() method can already handle an array of patterns to find a single match.

So it makes sense to pass the the variadic arguments directly to this method instead of a foreach loop or a collection method.

[taylorotwell]

If the code is not broken I don't want to change it.

[sebdesign]

It wasn't broken before #39857 either. I'm only suggesting this change because Collection::contains() is redundant here and does not provide anything that Str::is() cannot do.