Add traits for color schemes from traditional color theory

[Ogeon]

This adds traits for the complementary, split complementary, analogous, triadic and tetradic color schemes. A trait for the complementary color was requested in #383, but all of these may be useful.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 82.52033% with 43 lines in your changes are missing coverage. Please review.

Project coverage is 81.94%. Comparing base (c54efbd) to head (479beec).

Files	Patch %	Lines
palette/src/macros/color_theory.rs	76.00%	24 Missing :warning:
palette/src/serde/alpha_serializer.rs	24.00%	19 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #384 +/- ## ========================================== + Coverage 81.82% 81.94% +0.12% ========================================== Files 113 115 +2 Lines 18068 18277 +209 Branches 18068 18277 +209 ========================================== + Hits 14785 14978 +193 - Misses 3125 3141 +16 Partials 158 158 ```

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[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #384 will improve performances by 11.42%

_{Comparing color_theory (479beec) with master (c54efbd)}

Summary

⚡ 1 improvements ✅ 44 untouched benchmarks

Benchmarks breakdown

	Benchmark	master	color_theory	Change
⚡	matrix_inverse	271.1 ns	243.3 ns	+11.42%