Adding an option "Group member attribute" to LDAP Authentication Servers

[jakobsen-lrz]

Hello, i wanted to implement a feature for OPNsense concerning LDAP authentication. OPNsense always assumes that the LDAP attribute "memberof" is used to specify which groups a user is a member of. The Problem is that we use a completely custom LDAP attribute for this. So i wanted to add an Option "Group member attribute" to specify which Attribute to check.

I have already implemented this myself, and it seems to work without Problem on my OPNsense instance. I have a branch ready for a pull request, and have opened an issue regarding this, but i dont know how i should continue with this. Is this even something that would be accepted?