[MIRROR] Adds rolling up sleeves to the greyscale buttondown, adds greyscale suitskirt, minor buttondown resprite [MDB IGNORE] (#22952)

* Adds rolling up sleeves to the greyscale buttondown, adds greyscale suitskirt, minor buttondown resprite (#77404)

## About The Pull Request
I noticed some recent PRs were replacing some suits with the buttondown
+ slacks, which isn't a terrible idea, but these changes also removed
the suitskirt variants of these, as well as the buttondown not
supporting rolling up its sleeves
and more subjectively, I _really_ don't like the horizontal line on the
buttondown, makes you look fat, don't like it
so I decided to remedy these issues myself
<details>
<summary> Screenshots </summary>

Service suitskirt

![image](https://github.com/tgstation/tgstation/assets/138069572/ab79295b-7ef3-46db-a24c-4dc20d58cd96)
Rolled up sleeves

![image](https://github.com/tgstation/tgstation/assets/138069572/bc8ea25d-0e72-45cf-afc5-bcd23911ed04)
Rolled up sleeves sidesprite

![image](https://github.com/tgstation/tgstation/assets/138069572/78e85ae5-4f39-4885-a094-9b187b4b7186)
</details>
The skirt itself is a slightly modified version of the skirt from the
greyscale skirtleneck

I had to put it in the shorts_pants_shirts.dmi files for greyscale
config reasons, not sure if everything is named correctly or necessarily
in the right place here
## Why It's Good For The Game
Re-adding the removed suitskirts is more objectively a good thing, the
resprite is more subjective but honestly I was mostly motivated to make
this by my hatred for how the buttondown looked before so lol
I also noticed a minor bug that was implemented when the old black suit
was replaced with a variant of the slacks
## Changelog
🆑
add: Added greyscale suitskirt, available in clothesmates
add: You can now roll up the sleeves of greyscale buttondown shirts
qol: Re-added previously removed black suitskirt and the RD's tan
suitskirt, as pre-colored variants of the above
fix: Fixed only one buttondown with slacks being available in
clothesmates
image: Slightly adjusted greyscale buttondown sprite, you look less fat
now!
/🆑

* Adds rolling up sleeves to the greyscale buttondown, adds greyscale suitskirt, minor buttondown resprite

* Adds the new clothing to loadouts

* Modular icons

* Removing some bloat from a previous pr while we are at it

---------

Co-authored-by: siliconOpossum <138069572+siliconOpossum@users.noreply.github.com>
Co-authored-by: Pinta <68373373+softcerv@users.noreply.github.com>
Co-authored-by: Giz <13398309+vinylspiders@users.noreply.github.com>

code/game/objects/structures/crates_lockers/closets/secure/medical.dm

@@ -56,6 +56,7 @@
 /obj/structure/closet/secure_closet/psychology/PopulateContents()
 	..()
 	new /obj/item/clothing/under/costume/buttondown/slacks/service(src)
+	new /obj/item/clothing/under/costume/buttondown/skirt/service(src)
 	new /obj/item/clothing/neck/tie/black(src)
 	new /obj/item/clothing/shoes/laceup(src)
 	new /obj/item/storage/backpack/medic(src)