Canreach refactor (#93165)

## About The Pull Request
ports https://github.com/DaedalusDock/daedalusdock/pull/1144
ports https://github.com/DaedalusDock/daedalusdock/pull/1147

full credit to @Kapu1178 for the juice

instead of `reacher.CanReach(target)` we now do
`target.CanBeReachedBy(reacher)`, this allows us to give special
behavior to atoms which we want to reach, which is exactly what I need
for a feature I'm working on.
## Why It's Good For The Game
allows us to be more flexible with reachability
## Changelog
🆑
refactor: refactored how reaching items works, report any oddities with
being unable to reach something you should be able to!
/🆑

code/modules/mob/living/basic/pets/dog/corgi.dm

@@ -292,7 +292,7 @@
 			possible_headwear += item
 	if(!length(possible_headwear))
 		for(var/obj/item/item in orange(1))
-			if(ispath(item.dog_fashion, /datum/dog_fashion/head) && CanReach(item))
+			if(ispath(item.dog_fashion, /datum/dog_fashion/head) && item.IsReachableBy(src))
 				possible_headwear += item
 	if(!length(possible_headwear))
 		return