More Stasis Stuff (#21384)

This PR adds part upgrading for stasis beds, making it so that improving
the parts will also improve the stasis value provided by the bed.

I've also added new mechanics hints to both stasis beds and stasis bags
to help explain to players why they should totally be shoving dying
people into stasis.

---------

Signed-off-by: VMSolidus <evilexecutive@gmail.com>

code/game/objects/items/bodybag.dm

@@ -170,6 +170,12 @@
 	var/stasis_power = 20
 	var/degradation_time = 60 // 2 minutes: 60 ticks * 2 seconds per tick
 
+/obj/structure/closet/body_bag/cryobag/mechanics_hints(mob/user, distance, is_adjacent)
+	. += ..()
+	. += "Applies a [stasis_power]x stasis effect to any living creature stored inside this bag."
+	. += "This causes effects such as bleeding and brain damage to accumulate 10x slower."
+	. += "stasis bags will only last for [degradation_time] seconds before becoming useless. The bag will turn from blue to grey when this happens."
+
 /obj/structure/closet/body_bag/cryobag/feedback_hints(mob/user, distance, is_adjacent)
 	. += ..()
 	. += "The stasis meter shows <b>'[stasis_power]x'</b>."