Refactored Node3D rotation modes

[reduz]

• Made the Basis euler orders indexed via enum.
• Node3D has a new rotation_order property to choose Euler rotation order.
• Node3D has also a rotation_mode property to choose between Euler, Quaternion and Basis

Exposing these modes as well as the order makes Godot a lot friendlier for animators, which can choose the best way to interpolate rotations. The quaternion property is also very handy for tweening without Gimbal lock.
The new Basis mode makes the (exposed) transform property obsolete, so it was removed (can still be accessed by code of course).

[fire]

As part of the animation team, animators can't read quaternions and rotation modes helps key the proper rotations.

Looks good!

Will need to wait for tests.

[reduz]

@fire It is true that animators can't read quaternions. In fact, I don't think anyone really can, but having a quaternion exposed property is great for doing Gimbal-Lock free interpolation (simply add a key in the rotation). I think in a subsequent PR we could have something like a ball you can turn or something like this for editing quaternions but I think its out of the scope of this PR.

[lyuma]

@fire looked at this too.

Using Hide Whitespace, we validated that the code in set_euler and get_euler is identical to before.

It looks great. I was just curious about the DIRTY_VECTORS case.

Also small nit, but is there any reason to do variant accessors using VariantInternalAccessor<Basis::EulerOrder> rather than the VARIANT_ACCESSOR_NUMBER(Basis::EulerOrder) macro?

[lyuma]

Why is this calculating a new Basis matrix using Basis::from_euler() when data.local_transform.basis already exists?

Is this to avoid introducing error when scale is 0 or non-uniform?

[reduz]

I think it is because local_transform may be dirty (invalid)

[akien-mga]

Looks good to me.
Edit: Pending fix for https://github.com/godotengine/godot/pull/54084/files/6625ac317d064c747431ae7b7b2c4df31e948f61#diff-f322b5adb1e36fb871aa172a66a03f9225c591168728c972fd4ceadc3cd3121f, so wait before merging.

[akien-mga]

A GDScript test is now failing:

modules/gdscript/tests/gdscript_test_runner.cpp:179: ERROR: CHECK( result.passed ) is NOT correct!
  values: CHECK( false )
  logged: "/Users/runner/work/godot/godot/modules/gdscript/tests/scripts/runtime/features/stringify.gd"
          "GDTEST_ANALYZER_ERROR
No constructor of \"Basis\" matches the signature \"Basis(Vector3)\".
"

[reduz]

@akien-mga nice we have this now, let me see if I can fix it

[akien-mga]

Now it passes tests, just needs an update to the docs: https://github.com/godotengine/godot/runs/3997580689?check_suite_focus=true

[akien-mga]

Thanks!