The Group's front.php template hierarchy should include the current group type

[imath]

I think people would expect it as the member's front.php template hierarchy is including the member-type of the displayed user.

I know we're close to release, but i've said to myself let's try to have it in at the last minute :)

See attached patch.

[dcavins]

In 10891:

Add group-type-specific template to group front template hierarchy.

Add front-group-type-{type}.php template to group front template
hierarchy stack. Order of stack is now id, slug, type, status
and front.

Props imath.

Fixes #7129.