Add custom :page param

[kurenn]

On a conversation with @ddnexus and @cseelus we were discussing about the possibility of having a a configuration option for the :page param, rather than hard coding it to :page.

This should work for the 3 supported pagination gems(Pagy, Kaminari, WillPaginate)

Here are some notes:

From a (resolved) Pagy issue:

The ability to add arbitrary params similar to will_paginates :params option or Kaminaris option with the same name would be helpful for a number of use cases:

[…] (not applicable for API pagination)
Passing search/form params around, when Pagy is used in combination with a search function
Passing in a controller/action name (see will_paginate or Kaminaris docs)