there was already a tooltip as you hover over
each submission and the header menu let you mute/
unmute but I guess people wanted to see the little
'muted' icon in the header as well
in the process I broke it out into its own
handlebars template
fixes: #6804
test plan:
* mute an assignment
* go to gradebook2
* look for a little mute icon in the header of
that column like on gradebook1
Change-Id: If728a4f11241440d377264123c0824edf05f12b3
Reviewed-on: https://gerrit.instructure.com/8114
Tested-by: Hudson <hudson@instructure.com>
Tested-by: Jake Sorce <jake@instructure.com>
Reviewed-by: Jake Sorce <jake@instructure.com>
2bc8ebd637