refactoring in RT::Test was lost somewhere

Conflicts:
	inc/Module/Install.pm
	inc/Module/Install/AutoInstall.pm
	inc/Module/Install/Base.pm
	inc/Module/Install/Can.pm
	inc/Module/Install/Fetch.pm
	inc/Module/Install/Include.pm
	inc/Module/Install/Makefile.pm
	inc/Module/Install/Metadata.pm
	inc/Module/Install/Win32.pm
	inc/Module/Install/WriteAll.pm
	xt/ldap/basics.t
	xt/ldap/privileged.t

RT takes care to obfuscate top-level keys that look like passwords, but
doesn't dig deep into data structures.

Usernames with special characters—e.g. parens—were breaking all of our
normal filters.

This really only caused log messages, but they were confusing, and
CanonicalizeEmailAddress is run also.

Otherwise, most LDAP servers won't return the attribute and we'll think
it's undef.  Tests didn't uncover this bug because the test server
returns all attributes regardless of what's requested.

As reported in rt.cpan.org #62085.

Until we remove it and make sure it doesn't break anything, at least
avoid the warnings.

This is necessary when the group membership attribute (group_attr)
contains uids or email addresses or other values instead of the DNs of
users.

The new optional config param for LDAP sources is named
group_attr_value.

This means you no longer need to symlink this plugin's source into
/path/to/your/dev/rt/plugins/ in order to test.

Testing is now:

    prove -lv -I /path/to/your/dev/rt xt/*.t

This works for RT 3.8.6 and later.

Andrew Daugherity noted that things which will get a default value later
but which are undef coming back from LDAP will cause lots of warnings on
user creation or login.

Noticed by limako in #rt