iconGrid: Add PaginatedIconGrid

The new PaginatedIconGrid class acts as a container for pages.
So the new class provides  the container behaviour and some
useful functions like positions of pages, number of pages, etc.
But, it doesn't add indicators of the pages and doesn't manage
the scroll of the pages, neither any management of the pages
like in which page currently it is, etc.

https://bugzilla.gnome.org/show_bug.cgi?id=706081