Move most of the EE-specific LDAP code to EE-specific classes/modules
This will prevent or reduce merge errors. This doesn't include all of the EE-specific LDAP code, but it's the low-hanging fruit. I will get the less-straightforward stuff in a subsequent merge request to avoid making this one unbearably large.
Why is this necessary?
I'm starting work on some of the priority LDAP features/fixes. I was about to start stuffing additional EE-specific methods into Gitlab::LDAP::Adapter and it felt like this could be a CE-EE merge danger zone. This seemed like a potentially quick fix to that worry so I thought I'd take a moment to see if it was sane.
@DouweM and I talked briefly about this. It seems to be the way we want to go in the future anyway so this gets the ball rolling.
If this goes through and everyone is happy, I'll also create a subsequent merge request to add some development docs about organizing EE code.