gitlab-user-lookup: new utility script

This is a simple python script that uses the python3-gitlab library to do user lookups. Do you know someone's email address, but not their gitlab handle? Look it up. Know their handle, but not their public email address? Look it up. Know their kerberos ID email, but not sure if it's their public gitlab email address? Look it up.

Examples:

$ ./gitlab-user-lookup.py jwilson@redhat.com
Searching for users matching "jwilson@redhat.com"...
Found username: jwilsonrh (id: 6616462)
  public_email: jarod@redhat.com

$ ./gitlab-user-lookup.py dzickusrh
Searching for users matching "dzickusrh"...
Found username: dzickusrh (id: 4071264)
  public_email: dzickus@redhat.com

The less specific you are with your query, you may get more results.

$ ./gitlab-user-lookup.py jwilson
Searching for users matching "jwilson"...
...
<very long list of users, which does include jwilsonrh>
...

You can also feed it quoted names:

$ ./gitlab-user-lookup.py "Jarod Wilson"
Searching for users matching "Jarod Wilson"...
Found username: jarodwilson (id: 5639962)
  public_email:
Found username: jwilsonrh (id: 6616462)
  public_email: jarod@redhat.com

Signed-off-by: Jarod Wilson jarod@redhat.com