disband, reinstate PI groups

[simonLeary42]

This is a clone of #520 which I accidentally broke

Closes #392

Puts back the old "disband PI" functionality (removed in #207) using the term "disable" instead of "disband". A PI group can now have the isDisabled attribute set to "TRUE" and it will be ignored by the portal. If a PI is once again approved for a PI group, the old group will have isDisabled set to "FALSE" or unset.

Note: Disabled PI groups should have no members.

Note: I used OIDs 1.1.1 and 1.1.2 for my new LDAP stuff. 1.1 is documented as a "dead namespace" in OID land and is advisable for "private experiments". copilot doesn't like that I did this.

Note: if a large PI group is disabled by an admin, while updating the qualified status of each member, the portal will query for the members' attributes one-at-a-time and then do $user->getPIGroupGIDs() one-at-a-time, which is a lot of LDAP queries. I implemented an optimized version of this, but it's very ugly.

Test cases added:

• UnityGroup->setIsDisabled() changes return value of future UnityGroup->getIsDisabled()
• when user is re-approved and old disabled group is re-enabled, $user->isPI() returns true
• when PI group is disabled by an admin in pi-mgmt.php, $group->getIsDisabled() returns true and $owner->isPI() returns false
• when PI group is disabled voluntarily by the owner in pi.php, $group->getIsDisabled() returns true and $owner->isPI() returns false
• groups with isDisabled unset and groups with isDisabled = "FALSE" are both displayed in pi-mgmt.php
• when PI group is disabled, members become unqualified
• PI is not able to disable their group if the group still has members, but an admin can

Screen.Recording.2026-01-22.at.10.59.48.AM.mov