Namespace license checks for push rules

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

Push rules (EES / Bronze)

1. Do not show Push rules on repository settings page.

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

mentioned in issue #2582 (closed)

mentioned in issue #2335 (closed)

assigned to @to1ne

assigned to @nick.thomas and unassigned @to1ne

Push rules also have a presence in the admin dashboard:

Since namespace licensing is an AND proposition, we can hide this unless License.feature_available?(:push_rules)

mentioned in merge request !2335 (merged)

closed via merge request !2335 (merged)