CursorPaginator support for page_query_param

[cypreess]

I found it very usefull for frontend apps to set page size via query param when using CursorPaginator. I am attaching PR for that that is basically adoption of of PageNumberPagination approach inside CursorPaginator.

Disclaimer: I decided to leave both max_page_size and offset_cutoff as they are serving different semantic purpose (even if feels very similar).

[cypreess]

@tomchristie any chance doing a glance look at this?

[carltongibson]

Closed by #5250