Allow admins to unlink users from Jetpack

Situation:

Site uses WP.com SSO exclusively after a migration from using local accounts.
WP.com user is linked to User A.
User wants to start using existing, unlinked User B instead.
WooCommerce site, so no access to wp-admin for the user by design, so the user can't unlink.
Admin can't disassociate WP.com user to User A.

I banged my head against the desk realizing that under the above setup, I can *see* that the local User A is connected with the Jetpack logo in the users list table, but there is no option to unlink, flush the meta, etc, without adding a new code somewhere or having CLI access.

No files, tests, or entry points are named in the issue. Begin by locating Jetpack’s WP.com SSO user-linking and admin user-management entry points, then define and verify an administrator unlink workflow that lets the existing local account be used.

Written by the indexing model from the issue text.