Changed the track type inserted into the animation by the Inspector key button

[TokageItLab]

Note: RotationTrack insertion is broken. Euler and Quaternion conversions are needed, but maybe #54084 merge is needed for them.

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For performance considerations, the following 4 track types have been added to the animation by #53689 and #53865.

• Position3DTrack
• Rotation3DTrack
• Scale3DTrack
• BlendShapeTrack

However, the insertion of tracks from the Inspector's key buttons is still only allowed for ValueTrack or BezierTrack. BezierTrack still has its place, but for certain properties, we will change it to insert a new type of track instead of ValueTrack.

Although, there is no foolproof mechanism implemented to prevent ValueTrack from being directly generated or the pathname of ValueTrack from being rewritten by user interaction, it is outside the scope of this PR.

[TokageItLab]

Bezier tracks parse a single property into multiple tracks and insert them into the animation. So it was a bit of a hacky implementation to check if a Bezier track already exists. I think it should be refactored in the future when Bezier tracks are more organized.

[reduz]

I would just harcode the property paths that require these special keys in the editor, its anvery special case, not worth really doing it flexible.

[TokageItLab]

@reduz If there is no way to choose between Bezier tracks like in Skeleton bone's pose, simple hardcoding is fine.
However, if we want to allow the choice of Bezier track, such as in Node3D Transform, hard coding will cause code duplication, to avoid it, I ended up with a slightly larger implementation.

[TokageItLab]

@reduz If we expect to insert Bezier tracks in TRS/Blends tracks, you need to implement this.
But, if we don't want to insert Bezier tracks in the TRS/Blends track, but want to access the Bezier editor from the TRS/Blends track, you are right, a simpler implementation is possible.

[TokageItLab]

It is old. Perhaps the Transform3D Value/Bezier track will not be obsolete in Godot 4. Also, the rotation issue will be superseded by the QuaternionEditor implementation.