[5.7] Allow Model destroy method to accept a collection of ids

[tristanward]

Currently the destroy() method on an eloquent model accepts both an array of ids to destroy and a list of ids as arguments.

However, if the destroy method is given a Collection of ids (such as from a pluck()) it will destroy only the first id in the collection. This is potentially unexpected behaviour from the developers point of view as no error is seen and an item is removed from the database.

This PR checks the value passed to the destroy() method and if it is an instance of Collection calls the 'all()' method to convert it to an array.

[ahinkle]

Can you add a test for this?

[taylorotwell]

I don't like to do nested ternarys in the framework.

[tristanward]

I've removed the nested ternary and am now doing a separate check for the instance of Collection first.