R1:efb01bf34f60

Allow "MFA Required" objects to be edited without MFA if the edit is only creating inverse edges

Summary:
Depends on D19900. Ref T13222. See PHI873. When an object requires MFA, we currently require MFA for every transaction.

This includes some ambiguous cases like "unsubscribe", but also includes "mention", which seems like clearly bad behavior.

Allow an "MFA" object to be the target of mentions, "edit child tasks", etc.

Test Plan:
- Mentioned an MFA object elsewhere (no MFA prompt).
- Made an MFA…