Make hue `::from_degrees` and some `palette::cast::*` functions `const fn`

[Ogeon]

This makes the following functions const fn, as allowed by Rust 1.61.0:

• ::from_degrees for hue types
• palette::cast::into_array_ref
• palette::cast::from_array_ref
• palette::cast::into_uint_ref
• palette::cast::from_uint_ref

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #405 will degrade performances by 11.73%

_{Comparing const_fn (13368ac) with master (afa3b12)}

Summary

❌ 1 regressions ✅ 45 untouched benchmarks

:warning: _Please fix the performance issues or acknowledge them on CodSpeed._

Benchmarks breakdown

	Benchmark	master	const_fn	Change
❌	matrix_inverse	438.9 ns	497.2 ns	-11.73%

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.66%. Comparing base (afa3b12) to head (13368ac).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #405 +/- ## ========================================== - Coverage 82.66% 82.66% -0.01% ========================================== Files 127 127 Lines 19545 19539 -6 Branches 19545 19539 -6 ========================================== - Hits 16157 16151 -6 Misses 3285 3285 Partials 103 103 ``` | [Components](https://app.codecov.io/gh/Ogeon/palette/pull/405/components?src=pr&el=components&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Erik+Hedvall) | Coverage Δ | | |---|---|---| | [palette](https://app.codecov.io/gh/Ogeon/palette/pull/405/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Erik+Hedvall) | `82.71% <100.00%> (-0.01%)` | :arrow_down: | | [palette_derive](https://app.codecov.io/gh/Ogeon/palette/pull/405/components?src=pr&el=component&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Erik+Hedvall) | `81.98% <ø> (ø)` | |