Add personal labels to groups to allow group filtering

[Robert Lyon]

Have the ability that every person can label their groups. These labels can be used to filter groups on the "My groups" / "Groups" overview page Main menu -> Engage -> Groups and also to display only certain groups in the side bar and the block for groups on the profile page.
Note: please refer to https://select2.org/tagging for sample/demonstration control.

[Mahara Bot (dev-mahara)]

Patch for "master" branch: https://reviews.mahara.org/10442

[Mahara Bot (dev-mahara)]

Reviewed: https://reviews.mahara.org/10442
Committed: https://git.mahara.org/mahara/mahara/commit/eaf89f914bc301f1759f398feb9270dce88cc59e
Submitter: Robert Lyon (<email address hidden>)
Branch: master

commit eaf89f914bc301f1759f398feb9270dce88cc59e
Author: Robert Lyon <email address hidden>
Date: Mon Oct 14 14:24:00 2019 +1300

Bug 1848092: Add personal labels to groups

To allow for filtering by these labels (similar to tags) on
- the group index page
- in the mygroups block (on profile / dashboard pages)
- usr account setting to filter the list in sideblock

Adjusted the filtering to 'OR' join so you can display groups with
'cat' OR 'dog' labels

Change-Id: Id8c36f05b7dd27d9bf9b90722b2d66c6f3db877e
Signed-off-by: Robert Lyon <email address hidden>