FBX needs to support new animation system

[tlf30]

The FBX importer still imports animations with the old animation system. It needs to be updated to support the new system.

[stephengold]

For now, applications can use the AnimMigrationUtils class to convert loaded models to the new system. So this issue doesn't seem urgent.

[stephengold]

Given that how out-of-date our FBX importer is, we should perhaps abandon it or at least deprecate it. Most of the code dates from 2015, and the format has gone through many changes since then.

[Ali-RS]

Yeah, agree with you.

[tlf30]

That would probably be for the best. GLTF makes a great standard, and most workflows using FBX also now support GLTF.

[stephengold]

For v3.6.0, I've fixed a few of the more serious bugs in the FBX importer. However, it still has plenty of issues. My advice to JME developers would be to use a 3rd-party conversion tool such as https://github.com/godotengine/FBX2glTF or https://github.com/facebookincubator/FBX2glTF