Chainsaw weapon sprite bobbing isn't interpolated (unlike in GZDoom)

[Calinou]

• Related to https://github.com/Helion-Engine/Helion/issues/551.

Helion version: https://github.com/Helion-Engine/Helion/commit/3e60de303e27c74738b6e98e125ffb48a552c2cd

You can see interpolation is still slightly in effect if you move while holding a chainsaw, but it snaps between discrete positions every time the animation frame changes:

https://github.com/Helion-Engine/Helion/assets/180032/ec970153-fb5f-4e59-b21f-1f8a8b7c97ba

While vanilla Doom has the same issue, it's quite jarring compared to other weapons and should probably be changed to match GZDoom behavior.