owners: add gitlab usernames to mappings

We can't rely on mapping email addresses to gitlab usernames to assign reviews any longer, as any non-public email address will no longer return a username. The easiest thing to do here is to just include people's gitlab usernames in owners.yaml so we can use it directly, instead of having to look up emails to get handles.

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