Add tests file for Quaternion unit tests, with initial UTs

[codepatzer]

• Test constructors and quaternion product.
• Add test case for Axis-Angle construction about Y-axis.
• Add test case for xform of i-, j-, & k-unit vectors.
• Add test case for construction from Basis.
• Add test case for xform of arbitrary vector.
• Add stress test case: many Quaternions xform many vectors.
• Make comments consistent with style guide.

[fire]

@codepatzer I have enabled cicd checks.

Notes:

• https://docs.godotengine.org/en/stable/community/contributing/pr_workflow.html
• https://docs.godotengine.org/en/stable/community/contributing/testing_pull_requests.html

[codepatzer]

@codepatzer I have enabled cicd checks.

Notes:

* https://docs.godotengine.org/en/stable/community/contributing/pr_workflow.html

* https://docs.godotengine.org/en/stable/community/contributing/testing_pull_requests.html

Thanks for kicking off the checks! And thanks very much for the links. I see that I have not been following the process quite as the project lays it out. I will mend my ways in future, or at least move on to a new set of mistakes.

[codepatzer]

Rebased to have a single commit after checks passed, following a half dozen separate commits.

[codepatzer]

Rebased onto current upstream master branch.

[akien-mga]

Sorry for the late review. @codepatzer Are you available to rebase this PR and squash the commits? The test should also be moved to tests/core/math/test_quaternion.h.

[akien-mga]

Apologies for the delay reviewing this.

The tests look great! I force pushed an update to rebase and squash the commits, and did a few minor changes:

• Removed usage of M_PI and redefinition of deg2rad: we have all this already in core/math/math_defs.h and core/math/math_funcs.h so you just need to use those.
• Fix build issue for "Construct Basis Axes" since get_axis was renamed to get_column.
• The comment there about not being able to construct Basis from vectors may no longer be true, as there is a Basis(const Vector3 &row0, const Vector3 &row1, const Vector3 &row2) constructor. It's rows and not columns so might not be directly useful here though. I left it as is for now, could be revisited in a follow up PR.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉