[HL2] weapon_ar2.cpp still uses SMG activities so existing animations go unused

[THG327]

The AR2 still reuses SMG animations in its code despite NPC models having pre-existing unique AR2 animations that go unused as a result.

This issue is present in every release of the game including the latest 20th Anniversary Update meanwhile the models themselves have always been fully setup.

https://github.com/ValveSoftware/source-sdk-2013/blob/39f6dde8fbc238727c020d13b05ecadd31bda4c0/src/game/server/hl2/weapon_ar2.cpp#L55-L105

[pivotman319-owo]

I've opened a PR to address this: ValveSoftware/source-sdk-2013#1320

Before:

mod_episodic_win64_2025-05-31_16-42-11.mp4

After:

mod_episodic_win64_2025-05-31_19-36-23.mp4