Add route whereIn regex registration method

[emargareten]

This PR adds a whereIn regex registration method to check if the route parameters are contained within a given array.

Usage example:

Route::get('statuses/{type}')->whereIn('type', ['one', 'two', 'three']);

This will make sure type is equal to one of the values in the array.

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If possible, please consider releasing your code as a package so that the community can still take advantage of your contributions!

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[laserhybiz]

Implemented in #41794