Audits wash/cleaning signals + refactors wash() to ensure no needless mob updates occur (#91259)

## About The Pull Request

This has the potential to create a lot of needless mob updates which is
not great. Now should only update a mob's clothing if it was actually
washed.

This PR

1) ensures that all wash() procs return a bitflag.
2) ensures that `wash()` proccalls which result in expensive operations
like icon updates only do so when it is necessary

## Why It's Good For The Game

Updating mob sprites is expensive, and doing it when nothing has been
changed is bad.

## Changelog

Nothing really player facing

code/modules/mob/living/basic/bots/hygienebot/hygienebot.dm

@@ -123,7 +123,6 @@
 	for(var/mob/living/carbon/human in loc)
 		commence_wash(human)
 
-
 /mob/living/basic/bot/hygienebot/proc/generate_ai_speech()
 	ai_controller.set_blackboard_key(BB_WASH_FOUND, found_announcements)
 	ai_controller.set_blackboard_key(BB_WASH_THREATS, threat_announcements)