[REFACTOR] Consolidates SLOT_FLAG and SLOT_HUD into one ITEM_SLOT flag (#26743)

* IT WORKS UP UNTIL THIS POINT

* Consolidates SLOT_FLAG and SLOT_HUD into one

* Remove cover_both_ears

* SLOT_HUD to ITEM_SLOT

* Remove clothing_trait changes for the time being

* Remove accidental copy-paste

* Re-add no-slip var

* More failure to copy-paste correctly

* Leftover flag

* Combine left and right slot flags where possible

* UNGOOF MY DEFINES, PHAND IS NOT A THING

* Minor spacing changes

* Some more fixes from merge

* Seperates ITEM SLOT AMOUNT into two defines

* ON SECOND THOUGHT LETS NOT DO THAT.

* Addresses Contra's review

* Thank you GREP

* Rename ITEM_SLOT_FEET to ITEM_SLOT_SHOES

* Added a comment to the bitmasks in clothing defines

* Rename ITEM_SLOT_TIE to ITEM_SLOT_ACCESSORY

* These are for a seperate PR.

* Magboot fixes

* Requested changes

* Re-add accidental removal

* Wrong flags

* Update code/__DEFINES/clothing_defines.dm

Co-authored-by: Contrabang <91113370+Contrabang@users.noreply.github.com>
Signed-off-by: Chap <erwin@lombok.demon.nl>

* Requested changes

* Merge fixes

* Fix double headset

* Fixes multiple accessories

---------

Signed-off-by: Chap <erwin@lombok.demon.nl>
Co-authored-by: Adrer <adrermail@gmail.com>
Co-authored-by: Contrabang <91113370+Contrabang@users.noreply.github.com>

code/modules/client/preference/loadout/loadout_accessories.dm

@@ -13,7 +13,7 @@
 
 /datum/gear/accessory
 	main_typepath = /datum/gear/accessory
-	slot = SLOT_HUD_TIE
+	slot = ITEM_SLOT_ACCESSORY
 	sort_category = "Accessories"
 
 /datum/gear/accessory/scarf

code/modules/client/preference/loadout/loadout_glasses.dm

@@ -13,7 +13,7 @@
 
 /datum/gear/glasses
 	main_typepath = /datum/gear/glasses
-	slot = SLOT_HUD_GLASSES
+	slot = ITEM_SLOT_EYES
 	sort_category = "Glasses"
 
 /datum/gear/glasses/sunglasses

code/modules/client/preference/loadout/loadout_gloves.dm

@@ -13,7 +13,7 @@
 
 /datum/gear/gloves
 	main_typepath = /datum/gear/gloves
-	slot = SLOT_HUD_GLOVES
+	slot = ITEM_SLOT_GLOVES
 	sort_category = "Gloves"
 
 /datum/gear/gloves/fingerless

code/modules/client/preference/loadout/loadout_hat.dm

@@ -13,7 +13,7 @@
 
 /datum/gear/hat
 	main_typepath = /datum/gear/hat
-	slot = SLOT_HUD_HEAD
+	slot = ITEM_SLOT_HEAD
 	sort_category = "Headwear"
 
 /datum/gear/hat/hhat_yellow

code/modules/client/preference/loadout/loadout_racial.dm

@@ -20,29 +20,29 @@
 	display_name = "Tajaran veil"
 	description = "A common traditional nano-fiber veil worn by many Tajaran. It is rare and offensive to see it on other races. Can be combined with various other eyewear."
 	path = /obj/item/clothing/glasses/hud/tajblind
-	slot = SLOT_HUD_GLASSES
+	slot = ITEM_SLOT_EYES
 
 /datum/gear/racial/footwraps
 	display_name = "Cloth footwraps"
 	path = /obj/item/clothing/shoes/footwraps
-	slot = SLOT_HUD_SHOES
+	slot = ITEM_SLOT_SHOES
 
 /datum/gear/racial/handwraps
 	display_name = "Cloth handwraps"
 	path = /obj/item/clothing/gloves/handwraps
-	slot = SLOT_HUD_GLOVES
+	slot = ITEM_SLOT_GLOVES
 
 /datum/gear/racial/vox_casual
 	display_name = "Vox jumpsuit"
 	description = "These loose clothes are optimized for the labors of the lower castes onboard the arkships. Large openings in the top allow for breathability while the pants are durable yet flexible enough to not restrict movement."
 	path = /obj/item/clothing/under/vox/vox_casual
-	slot = SLOT_HUD_JUMPSUIT
+	slot = ITEM_SLOT_JUMPSUIT
 
 /datum/gear/racial/vox_robes
 	display_name = "Vox robes"
 	description = "Large, comfortable robes worn by those who need a bit more covering. The thick fabric contains a pocket suitable for those that need their hands free during their work, while the cloth serves to cover scars or other injuries to the wearer's body."
 	path = /obj/item/clothing/suit/hooded/vox_robes
-	slot = SLOT_HUD_OUTER_SUIT
+	slot = ITEM_SLOT_OUTER_SUIT
 
 /datum/gear/racial/plasmamansuit_coke
 	display_name = "Coke Suit"

code/modules/client/preference/loadout/loadout_shoes.dm

@@ -13,7 +13,7 @@
 
 /datum/gear/shoes
 	main_typepath = /datum/gear/shoes
-	slot = SLOT_HUD_SHOES
+	slot = ITEM_SLOT_SHOES
 	sort_category = "Shoes"
 
 /datum/gear/shoes/sandals

code/modules/client/preference/loadout/loadout_suit.dm

@@ -13,7 +13,7 @@
 
 /datum/gear/suit
 	main_typepath = /datum/gear/suit
-	slot = SLOT_HUD_OUTER_SUIT
+	slot = ITEM_SLOT_OUTER_SUIT
 	sort_category = "External Wear"
 
 //WINTER COATS

code/modules/client/preference/loadout/loadout_uniform.dm

@@ -14,7 +14,7 @@
 // Uniform slot
 /datum/gear/uniform
 	main_typepath = /datum/gear/uniform
-	slot = SLOT_HUD_JUMPSUIT
+	slot = ITEM_SLOT_JUMPSUIT
 	sort_category = "Uniforms and Casual Dress"
 
 /datum/gear/uniform/suit