Be prescriptive on archived repos (including removing permissions)

[BigLep]

Problems

1. github-mgmt YAML files can be unwieldy in part because of archived repos (see Remove clutter resulting from archived repos #115). One of the reasons is that the archived repos still have access permissions listed.
2. Archived repos that have users/teams associated can be a security vulnerability. If a malicious (likely compromised) repo admin unarchives it, they could introduce bugs, vulnerabilities, etc.

Ideas

1. When archiving a repo, remove all direct repo permissions (members and teams). In order to unarchive, someone would need to unarchive and add permissions through github-mgmt. In addition to reducing clutter while in an archived state, this is good because it gives clear visibility to a significant repo event (e.g., unarchiving).
   • In addition to doing things like removing repo permissions, I could imagine to doing other actions like moving the repo to a separate YAML file as discussed in Remove clutter resulting from archived repos #115.
2. Even if one doesn't want this to be an automated step, this could be a one-off script/check that somebody runs. I assume a backfill operation of "remove permissions from archived repos" requires some sequencing though in that it would need to first be unarchived, have the permissions removed, and then be archived.