Bools and returns super-pr (#53221)

Replaces like 70-80% of 0 and such, as a side effect cleaned up a bunch of returns
Edit: Most left out ones are in mecha which should be done in mecha refactor already
Oh my look how clean it is

Co-authored-by: TiviPlus <TiviPlus>
Co-authored-by: Couls <coul422@gmail.com>

code/modules/mining/lavaland/ash_flora.dm

@@ -30,7 +30,7 @@
 
 /obj/structure/flora/ash/proc/harvest(user)
 	if(harvested)
-		return 0
+		return FALSE
 
 	var/rand_harvested = rand(harvest_amount_low, harvest_amount_high)
 	if(rand_harvested)
@@ -49,7 +49,7 @@
 	desc = harvested_desc
 	harvested = TRUE
 	addtimer(CALLBACK(src, .proc/regrow), rand(regrowth_time_low, regrowth_time_high))
-	return 1
+	return TRUE
 
 /obj/structure/flora/ash/proc/regrow()
 	icon_state = base_icon