feat: Sort by CFP date

[bendechrai]

Add a Sort to the filters tab and sort by CFP End Date or Event Start Date

Solves #752

[scraly]

Thanks for your PR :-)
With your sort code, I've created the #1282 PR that display the CFP in a special view.

I think this kind of cfp view can be very helpful because sometimes we want to have information events (list, calendar and map views) and sometimes we only want opened CFP that will close :)