feat(math/unstable): add math package with basic math utilities

[lionel-rowe]

Closes #6803

• clamp: Clamp a number within a range. Based on Math.clamp proposal, with a notable difference being that current proposal specifies TypeErrors for NaN inputs, whereas my version returns NaNs, because throwing TypeErrors seems rather unexpected given the corresponding behavior of Math.min and Math.max.
• modulo: Floor modulo operation, in contrast with JS's % remainder operator. Based on Python's % (floor modulo) operator and modulus math proposal.
• round-to: Round a number to a specified number of decimal places using various rounding strategies. Basically Number#toFixed but returning a number instead of a string.

Probably worth kicking the wheels for things like floating-point rounding issues, in cases where those are avoidable or optimizable.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.08%. Comparing base (9f9af1d) to head (1611154).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6823      +/-   ##
==========================================
- Coverage   94.09%   94.08%   -0.01%     
==========================================
  Files         578      582       +4     
  Lines       42654    42683      +29     
  Branches     6781     6788       +7     
==========================================
+ Hits        40134    40160      +26     
- Misses       2469     2471       +2     
- Partials       51       52       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[kt3k]

I often find these utils useful in my personal projects (Especially modulo is necessary for geometry-related programming). I'm in favor of the idea. LGTM

Does anyone have concern/objection about having this (unstable) package?

cc @ry @piscisaureus @bartlomieju