Improve list groups roles performance

Uses GET v3/role_assignments?scope.project.id=<project_id>
to fetch groups roles in a given project, instead of doing
an individual call for every known group.

Closes-Bug: 1369137
Change-Id: Ie64dfddc0d8cbb4f22f3ee3b19c248ca6973e96c
Fix E128 errors in openstack_dashboard/dashboards/admin/

E128 continuation line under-indented for visual indent

Partial-Bug: #1375929
Change-Id: I7a258d624f35b602da07c9b8604fb26c63287824
Fix E127 errors in remaining openstack_dashboard/

E127 continuation line over-indented for visual indent

Also fixes E127 introduces by other reviews
after other E127 fixes were merged.

Closes-Bug: #1375931
Change-Id: I0a09f1c2f74c707fc8a347f0ea5975bf2679976e
Merge "Improve list groups roles performance"
Merge "Fix E128 errors in openstack_dashboard/dashboards/admin/"
Merge "Fix E127 errors in remaining openstack_dashboard/"