More robust negativePiToPi, zeroToTwoPi, and mod

[IanLilleyT]

CesiumMath.negativePiToPi, CesiumMath.zeroToTwoPi, and CesiumMath.mod were applying extra math to values that were already in the valid range, causing floating point error.

For example:

console.log(0.1);
>>> 0.1
console.log(Cesium.Math.mod(0.1, 1.0));
>>> 0.10000000000000009

Ultimately the floating point error occurs in: ((m % n) + n) % n inside CesiumMath.mod.

The fix was to early-out if the input was already in the correct range.

Fixes #9312

[cesium-concierge]

Thanks for the pull request @IanLilleyT!

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Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

[lilleyse]

Thanks @IanLilleyT

As an extra precaution I confirmed that other tools give the same mod results for the negative number cases in MathSpec.

Unit tests pass locally and confirmed this fixes #9312