R1:ff49d1ef776b

Allow "bin/auth recover" to generate a link which forces a full login session

Summary:
Depends on D19902. Ref T13222. This is mostly a "while I'm in here..." change since MFA is getting touched so much anyway.

Doing cluster support, I sometimes need to log into user accounts on instances that have MFA. I currently accomplish this by doing `bin/auth recover`, getting a parital session, and then forcing it into a full session in the database. This is inconvenient and somewhat dangerous.

Instead, allow…