group leaders can edit group name

students who are made group leaders can update
the group name from the group dashboard page

fixes CNVS-11835

test plan:

- make a student a group leader
- visit the group dashboard as the group leader
- change the name as the group leader

Change-Id: I5637f1ef4e423a06f45987e0eccff2e65ac94613
TODO: Add description
Reviewed-on: https://gerrit.instructure.com/35326
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ethan Vizitei <evizitei@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Drew Bowman <dbowman@instructure.com>