Namespace license checks for locking project membership to members of a group

Related to https://gitlab.com/gitlab-org/gitlab-ee/issues/2335

Lock project membership to the members of a group (EES / Bronze)

1. Do not display Share with group lock on group settings page.

2. How to handle for future cases where this has already been set?

Brought to CE in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3186

closed

mentioned in commit ae51989e

mentioned in commit ab62efdb