Tag alias: hat_removed -> headwear_removed

Tag alias:

• hat_removed -> headwear_removed

• (And these, by extension: hat_off -> headwear_removed; headwear_off -> headwear_removed)

Reason:

I wouldn't call Sakuya's removed maid headdress (post #995988) a "hat".

P.S.: We have alternate headwear, too, but it's underused with its three pages only.

There is also helmet_removed, which also counts as "headwear". Perhaps we can make these implications and not aliases?

Did these:
create implication hat_removed -> headwear_removed
create implication helmet_removed -> headwear_removed
create alias headwear_off -> headwear_removed