Add ACT_PRIMARY_VM_RELOAD_4 for a new Rocket Jumper Viewmodel

[Ashe-tf]

Description

This PR adds a new activity, ACT_PRIMARY_VM_RELOAD_4, that is meant to be used for a new Rocket Jumper reload animation. Currently, it reuses the default rocket launcher reload loop and, thus, Soldier's arm clips into the Jumper barrel.

Desktop.2026.09.07.-.18.42.41.04.mp4

This PR only adds the activities. The following changes are required for it to work.

• Using the animation files from my Workshop fix ( https://steamcommunity.com/sharedfiles/filedetails/?id=3007375499 ), a new sequence needs to be created. For example:

$sequence rocket_jumper_reload_loop "animations/dmx/c_rocketjumper_all" {
	snap
	frames 75 100
	fps 30
	loop
	fadein 0.2
	fadeout 0.2	
	activity ACT_PRIMARY_VM_RELOAD_4 1
	event 5004 2 "Weapon_RPG.Reload"
	event AE_WPN_INCREMENTAMMO 10 " "
}

• In items_game.txt, we need to add a "animation_replacement"

"237"
		{...
			"visuals"
			{
				"sound_single_shot"	"Weapon_Rocket_Jumper.Single"
				"sound_special1"		"Weapon_Rocket_Jumper.Explode"
				"animation_replacement"
				{
					"ACT_VM_RELOAD"	"ACT_PRIMARY_VM_RELOAD_4"
				}
			}
		}

And that would be it. I tested it in-game using a custom item schema.

In the past, I've also made new third person animations for the Reload, however, the glaring issue is clearly the VM, I was not the best animator, and I believe that only the VM should be enough.