[TF2] Fixed war paint items not displaying rarity color in various UI

[rabscootle]

Partial fix for ValveSoftware/Source-1-Games#3520

This PR fixes rarities not applying properly in various UI when handling war-painted items.

When dealing with dropped weapons, the live TF client currently typically points to static data in the item schema for weapon details, including item rarities. However, War Paint items bypass requiring their own respective schema entries by having attributes applied to individual instances of base paintkit items. This change meant that while the same attributes are present on war paint items, certain game code was not updated to support this:

Game code has been updated to extract details from dropped weapons rather than static schema entry to display rarity for War Paints in the following UI:
Weapon Pickup (Target HUD)

Loadout - Item Selection Screen

Player Status HUD (when using dropped weapon)

[JoriKos]

The Park Pigmented Scattergun in the last image may be hard to read due to being red on red. Potentially the same issue with Mercenary grade weapons on BLU. I also personally find the purple Pistol text to be difficult to read. Is there a chance there can be a convar toggle to keep old behaviour?

[rabscootle]

The Park Pigmented Scattergun in the last image may be hard to read due to being red on red. Potentially the same issue with Mercenary grade weapons on BLU. I also personally find the purple Pistol text to be difficult to read. Is there a chance there can be a convar toggle to keep old behaviour?

I can look into making a convar, but this PR is focusing solely on bringing feature parity to War Paint items so they function closer to Decorated Weapons.