Adds more underwear for Kepori and digitigrades (shiptest-ss13#2690)

## About The Pull Request

Adds a bunch of new socks and shirts for Kepori, and digitigrade
versions of the pride and grayscale thigh-highs.
I also updated some of the already existing socks (like bee and bisexual
socks) to use the sprites of their grayscale counterparts as a base so
they're not just a flat sprite.
On top of this I noticed Kepori their left arms and legs also had right
arm and leg sprites and vice versa when facing east/west, so I removed
the extra parts from those. In practice there will be no noticeable
difference in this outside of amputees now showing their sides
correctly.

## Why It's Good For The Game

Now you can express your pride as a Kepori or with digitigrade legs!

## Images
Kepori with the tank top and the bee socks

![image](https://github.com/shiptest-ss13/Shiptest/assets/43698041/413f292b-10c2-4423-9fa2-fec28ace4efb)
Kepori with a polo shirt and nonbinary socks

![image](https://github.com/shiptest-ss13/Shiptest/assets/43698041/750a5ce0-e162-4d5a-9507-47f026e7cc59)
Lizard with the trans socks

![image](https://github.com/shiptest-ss13/Shiptest/assets/43698041/c296e97a-e636-4257-b50a-6743b60dc4c3)

## Changelog

:cl:
imageadd: Added more Kepori socks
imageadd: Added more Kepori shirts
imageadd: Added digitigrade pride thigh-highs
fix: Fixed Kepori arms having both left and right sprites per single arm
/:cl: