Allow more optional values for the 'showmore' pagination

[Robert Lyon]

Currently there are two hardcoded options, 'group' and 'institution', but it would be easier if we just passed in an array and looped thru it.

That way we can send other optional values at a later date

To test:

Make sure the 'Show more' button still works like before for portfolio page lists in user / group / institution / site areas

[Mahara Bot (dev-mahara)]

Patch for "master" branch: https://reviews.mahara.org/10031

[Mahara Bot (dev-mahara)]

Reviewed: https://reviews.mahara.org/10031
Committed: https://git.mahara.org/mahara/mahara/commit/e0df7f630edd14e8efac801b5161bd98573941b0
Submitter: Robert Lyon (<email address hidden>)
Branch: master

commit e0df7f630edd14e8efac801b5161bd98573941b0
Author: Robert Lyon <email address hidden>
Date: Tue May 21 12:14:40 2019 +1200

Bug 1829803: Allow more optional values for the 'showmore' pagination

This way if we need to use the showmore paginator elsewhere and
need to pass thru things like viewid, blockid we can

Also change the 'Show more' button from being a <div> to a <button>

behatnotneeded

Change-Id: I6c645016b5e9b141aabd2233e4fc9251a0088a69
Signed-off-by: Robert Lyon <email address hidden>