feat: promo items

[KiIoOnline]

Brings back limited time promotional cosmetic items for coop. Under cheats as I am not sure if it should be allowed. Linux support is needed.

[ThisAMJ]

As I said in commit comment:

complete redesign of how the command works lol
idk what/how to test this so lmk if i broke it

I do have an Unusual Prince Tavish's Crown in my TF2 inventory, is this change for the strange effects or just like force-enabling the roll cage or something?

[KiIoOnline]

This command force-enables all the pre-order weapon cosmetics like the roll cage, doesn't do anything else.
I tested the new changes on my end and it seems that it is not working as intended.
How I tested the command was as follows:

1. Load into any coop map with cheats enabled
2. Input the command with the desired changed (i.e "sar_set_promo_items_state all")
3. Restart the level and taunt to see if the changes took effect

The command goes through and no help messages are printed into the console, but no changes take effect on the player with any of the commands.