AnimationTree doesn't blend different track types

[TokageItLab]

Godot version

3.x, 4.0.dev

System information

MacOS X, Windows 10

Issue description

AnimationTree doesn't blend different track types.

Steps to reproduce

For example, there are two animations, A and B, and one object O.

• In animation A, the object O is moved using the ValueTrack.
• In animation B, the object O is moved using the BezierTrack.

If you blend Animation A and Animation B, they will not blend and only one of them will play.

Related issues

• AnimationTree does not apply Call Method Track for a method in an AudioStreamPlayer script. #48526
• Bezier tracks can't fade in/out animations with AnimationTree #43848

This is also the case when a Transform3DTrack is mixed in. Also, some tracks are generated by importing, while others are generated by pressing the key button in the inspector, so it is not easy to unify track types.

Minimal reproduction project

track_blends.zip (Godot 4.0 project file)