Corrects 200+ instances of "it's" where it should've been "its" instead (#85169)

## About The Pull Request

it's - conjunction of "it" and "is"
its - possessive form of "it"

grammar is hard, and there were a lot of places where "it's" was used
where it shouldn't have been. i went and painstakingly searched the
entire repository for these instances, spending a few hours on it. i
completely ignored the changelog archive, and i may have missed some
outliers. most player-facing ones should be corrected, though
## Why It's Good For The Game
proper grammar is good

## Changelog
🆑
spellcheck: Numerous instances of "it's" have been properly replaced
with "its"
/🆑

code/controllers/subsystem/timer.dm

@@ -645,7 +645,7 @@ SUBSYSTEM_DEF(timer)
 				hash_timer.hash = null // but keep it from accidentally deleting us
 			else
 				if (flags & TIMER_OVERRIDE)
-					hash_timer.hash = null // no need having it delete it's hash if we are going to replace it
+					hash_timer.hash = null // no need having it delete its hash if we are going to replace it
 					qdel(hash_timer)
 				else
 					if (hash_timer.flags & TIMER_STOPPABLE)