Geo: Add other status checks

Other things we should add:

• Compare time/date sync between primary and secondaries
• Compare replication lag (this can probably only done accurately by comparing master WAL timestamp vs secondary) gitlab-org/gitlab-ee!1610

mentioned in issue #3195

changed the description

Replication lag is already covered in !1610 (merged) (see also gitlab-org/gitlab-ee#1929).

Clock synchronization is being designed:

marked this issue as related to #3195

added feature proposal label