…items (knight armor, tiles) (#1874)

* Material datum color update, plus touching up some material items (knight armor, tiles) (#82500)

## About The Pull Request

Tries to bring the material datum colors in closer approximation to the
stacks they're attached too. I literally used the colors on the stacks.
some might need to be lighter or darker, but for the most part they'll
look...closer to their actual material hues.

![material datum stuff
2](https://github.com/tgstation/tgstation/assets/40847847/a3a5968f-cab3-43dd-8699-3dae879b21fb)

I've also tweaked the sprites of both the tile object and the actual
material tile turf to give it the right shading.


![image](https://github.com/tgstation/tgstation/assets/40847847/56489479-8774-492b-b8cc-aeabc6c0a67f)

In addition to the tiles, I've also updated the knight armor and helmet
to look closer to the much higher quality plate armor already in the
game.

## Why It's Good For The Game

It bothered me that the material datum coloring was inconsistent with
the actual colors used for the material stacks. When they were updated,
and even before they were updated, material datum stuff just never
looked _right_. I wanted to change that so that it looks just right.

I did not like the old material knight armor whatsoever. It was a
dithered mess, and seemed to already use parts of the standard plate
armor but with all the actual shading removed or replaced with the wrong
colors. This fixes that so that the armor is actually readable for what
it is.

## Changelog
:cl:
image: Updates the colors of various material datum to bring them closer
in-line with their actual material stacks
image: Improves the sprites for the material knight armor and helmet.
/:cl:

* Material datum color update, plus touching up some material items (knight armor, tiles)

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Co-authored-by: necromanceranne <[email protected]>