Add classic, recursive membership validators
GitHub::Ldap is a class

How could I forget.
Fix doco for MembershipValidators module
Missed Base
Significant fixes and :nail_care:
Add rudimentary tests for MembershipValidators
Doco base methods
CNs are hardcoded elsewhere
Accept String DN for member_filter
Use member_filter for Recursive group search
Remove FIXME
Extract attributes
Fix subgroup fixture CNs

Didn't match DN so resulted in false positives.
Add recursion tests for classic, recursive strategies
Autoload MembershipValidators::Base too

h/t @jch
Tweak docs
Document attrs, make internal method private
Refer to full class name in docs
Give these blocks some breathing room
Accept UID String for posix_member_filter