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/modular_computers/file_system/programs/virtual_pet.dm

@@ -175,10 +175,12 @@ GLOBAL_LIST_EMPTY(virtual_pets_list)
 /datum/computer_file/program/virtual_pet/proc/post_cleaned(mob/source, mob/user)
 	SIGNAL_HANDLER
 
+	. = NONE
 	source.spin(spintime = 2 SECONDS, speed = 1) //celebrate!
 	happiness = min(happiness + PET_CLEAN_BONUS, max_happiness)
 	COOLDOWN_START(src, on_clean_cooldown, 1 MINUTES)
 	START_PROCESSING(SSprocessing, src)
+	. |= COMPONENT_CLEANED|COMPONENT_CLEANED_GAIN_XP
 
 ///manage the pet's hat offsets when he changes direction
 /datum/computer_file/program/virtual_pet/proc/on_change_dir(datum/source, old_dir, new_dir)