Show installed component versions after GDK update

The following discussion from !1031 (merged) should be addressed:

• @tigerwnz started a discussion: (+1 comment)

  Thanks @cablett! I think this would definitely be useful to others.

  I've suggested a minor change to get it working, and I have one further question - what do you think about also printing a version summary at the end of an update? For example something like (not a complete list):

  Updated as of 2020-01-16 11:07:05:
  - gitlab-shell v11.0.0
  - gitlab-workhorse v8.19.0
  - gitlab-pages v1.13.0
  - gitaly v1.80.0

  (Of course, this can be done in a follow up if you prefer)