Waist sashes

BUR #31336 has been approved by @nonamethanks.

create implication waist_sash -> sash

Seems obvious enough. Shoulder sash already implies sash, so it follows that the other common type should as well.

(I considered adding an optional imply obi -> waist_sash BUR here, then decided that 80,000 obis would just pointlessly obfuscate the 500 or so other waist sashes).

The bulk update request #31336 (forum #306698) has been approved by @nonamethanks.