Being drunk or having a broken arm hurts accuracy with ranged weapons. Also cleans up a fair bit of hand handling to be more readable (#87904)

## About The Pull Request

1. Having a broken arm will affect your accuracy when firing a weapon
with that arm, even potentially causing damage to you if it's a weapon
with recoil. This effect is not applied under the effects of a
painkiller.

2. The sister effect of this (punching someone with a broken arm) now
also has an interact with painkillers (it can no longer block your
attack).

3. Being drunk heavily affects ranged weapon accuracy, unless you're the
bartender

4. A lot of hand handling cleanup, using new macros to make it a lot
more readable at a glance

## Why It's Good For The Game

We have this system for modifying firearm accuracy but we don't really
use it commonly, and I feel like it slots in well with a lot of places

For broken arms, it adds some more depth to the wound system, in the
same way that trying to punch someone with a broken arm causes pain. (I
actually want to expand this to melee weapon accuracy and attacking with
melee weapons in general, but that's for a later time)

For drunkenness, it just adds to the drunk shenanigans. It also slightly
reduces the effectiveness of drinks as combat healing chemicals, such as
quadsec - makes it a bit more of a trade off.

## Changelog

🆑 Melbert
balance: Having a broken arm affects your accuracy with ranged weapons
fired with that arm. Utilizing a painkiller will nullify this effect,
however.
balance: Painkillers will prevent your punches from being cancelled due
to having a broken arm. You'll still take damage, though.
balance: Being drunk now affects your accuracy with ranged weapon. The
bartender is immune to this effect via their skillchip.
code: A lot of code involving left and right hand handling has been
cleaned up, easier to read. Report any oddities, like left and rights
being flipped
/🆑

code/modules/tutorials/tutorials/switch_hands.dm

@@ -38,7 +38,7 @@
 
 /datum/tutorial/switch_hands/proc/create_hand_preview(initial_screen_loc)
 	hand_preview = animate_ui_element(
-		"hand_[hand_to_watch % 2 == 0 ? "r" : "l"]",
+		"hand_[user.held_index_to_dir(hand_to_watch)]",
 		initial_screen_loc,
 		ui_hand_position(hand_to_watch),
 		TIME_TO_START_MOVING_HAND_ICON,
@@ -50,7 +50,7 @@
 
 	switch (stage)
 		if (STAGE_SHOULD_SWAP_HAND)
-			var/hand_name = hand_to_watch % 2 == 0 ? "right" : "left"
+			var/hand_name = IS_RIGHT_INDEX(hand_to_watch) ? "right" : "left"
 			show_instruction(keybinding_message(
 				/datum/keybinding/mob/swap_hands,
 				"Press '%KEY%' to use your [hand_name] hand",