Removes bad nodamage var from projectiles, fixes Juggernaut / Rust Walker projectiles doing zero damage (#73806)

## About The Pull Request

- Juggernaut and Rust Walker projectiles were subtyped off of magic,
which is `nodamage`.

- The juggernaut actually had a copy+paste error with their type
`on_hit` which caused none of their special effects on hit ("relative
patching catches this")

- Then I realized projectiles have this var `nodamage` which is, for all
intents and purposes, just `damage > 0`. it's not checked for pacifism,
it's just that. This is dumb. So very dumb, so I removed it.
- There are, however, a few situations which used it in a unique way,
such as the blast wave cannon. This is why I replaced it with a proc,
`is_hostile_projectile`, for certain situations to actually find out if
the projectile is damaging. Projectiles can override this on a per type
basis by default, damaging projectiles = hostile.
- This has a chance to break some things, but I ... kinda doubt it will.

Fixes #73756

## Why It's Good For The Game

Projectiles that act as they should, less dumb vars

## Changelog

🆑 Melbert
fix: Fixes Juggernaut / Rust Walker projectiles doing zero damage
fix: Fixes Juggernaut projectiles not doing bonus damage to nearby
structures
code: Removed projectile nodamage var, replaces it with just checking
for damage
/🆑

code/datums/components/explodable.dm

@@ -87,7 +87,7 @@
 /datum/component/explodable/proc/projectile_react(datum/source, obj/projectile/shot)
 	SIGNAL_HANDLER
 
-	if(shot.damage_type == BURN && !shot.nodamage)
+	if(shot.damage_type == BURN && shot.damage > 0)
 		detonate()
 
 ///Called when you attack a specific body part of the thing this is equipped on. Useful for exploding pants.