Show 'Members not loaded' in 'Assigned members' when list isn't loaded yet

Feature

Populate 'assigned members' list with a 'members not loaded' string when members aren't loaded instead of showing an empty list.
Might also add 'Loading...' if request for members was made. String might benefit from some sort of highlight be that color or style, but plain string should be enough.

Reason

It's confusing to see an empty 'assigned members' list, showing a basic 'not loaded' string should promt user to check member list instead of thinking that something broke.

Test plan (?)

• Clear the cache
• Log in
• Open a group info floater
• Select Roles & Members section.
• The Roles tab should have focus by default.
• Select a Role that has some users in it.
• Verify the Assigned Members section says "Members List not Loaded"
• Click the Members tab. This loads the members.
• Click the Role tab.
• Select a Role that has some users in it, again.
• Verify the Assigned Members section now shows the actual member names.