Unreal: Standalone loader for animation

[antirotor]

Note

This is port of ynput/ayon-core#581 from ayon-core. For comments and review notes, please have a look at the conversation in the original PR.

Changelog Description

Implemented a standalone loader for animation that do not require a layout to be loaded first.

Additional info

Loader for Animation in Unreal is heavily based on the original solution using Blender and Unreal. Animation published from Maya doesn't have that layout json and so loading such animation will fail.

[LiborBatek]

I was able to load skeletonMesh and skeletonAnim products into UE 5.4 and successfully place an actor into the active level.

All seems working fine.

There is still need to apply rotate X 90 deg on the actor to be correctly aligned with UE World and matching maya world orientation tho.

there is a an actor option which helps but just when not replaying the anim unfortunately... the asset set pos correctly when not realtime mode active.

[antirotor]

I can't find reasonable combination where you either see correct orientation in the editor and wrong during playback, or vice-versa - or without rotating instantiated actor 90 degrees. Lets try to solve it in another PR.