Importing GLTF doesn't specify interpolation for aiNodeAnim type

Describe the technical debt Animation types in the .gltf importer are not exposed (at least not to the C API).

Better solution I suggest adding an mInterpolation field to the aiNodeAnim class, and using Interpolation_LINEAR as a default value for filetypes that don't support specifying the type of interpolation; that way different animation channels can use different interpolation methods (mimicking how .gltf specifies interpolation types).

Desktop (please complete the following information):

• OS: NixOS 24.05
• Browser: firefox
• Version: 5.4

Additional context This issue is pretty much a bump of #4890 since I'm actually trying to use the exact same file that issue's OP was trying to use.