Enhance Mass mention protection to account for display name mentions.

[FSG-Cat]

The current mass mention protection works based on intentional mentions but as our spammer doesnt use them that wont help.

Mjolnir has this feature in a PR or an issue already.

Label Logic:
L3 as some users are under attack as far as we know. As in we know they use Draupnir and are under attack.
P3 the attack this protection helps with is of a outrageous severity.
T5 This is iffy but well its a major attack and this is one of the most effective protections Draupnir has to protect from this attack so this label could change.

[Gnuxie]

I don't think we'll do this unless it turns out SetMembership is already caching displaynames.

[FSG-Cat]

understandable atleast we have a tracking issue for it and its important.