Add Rgb::from_hex and implement parsing for u16, u32, f32, f64

[Ogeon]

This expands hexadecimal parsing for Rgb to support more component types (u16, u32, f32, f64) and add an easier to find from_hex constructor for both Rgb and Rgba. It also updates component conversion when increasing bit depth to not convert via floating point types.

Closed Issues

• Closes Parsing hex strings as Rgb<f32> and Rgb<f64> #420.
• Closes Function to parse both hex and named colours from a string #306, by adding a from_hex constructor to Rgb.

Type Inference Breaking Change

This affects type inference by making Srgb::from_str(hex)?.into_format() and similar situations ambiguous. This example can be resolved by either specifying the component type or removing .into_format().

[codspeed-hq]

CodSpeed Performance Report

Merging #424 will not alter performance

_{Comparing more_hex (d626898) with master (8e22189)}

Summary

✅ 47 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 81.59722% with 53 lines in your changes missing coverage. Please review.

Project coverage is 82.63%. Comparing base (8e22189) to head (d626898).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #424      +/-   ##
==========================================
+ Coverage   82.61%   82.63%   +0.01%     
==========================================
  Files         130      131       +1     
  Lines       20254    20485     +231     
  Branches    20254    20485     +231     
==========================================
+ Hits        16733    16927     +194     
+ Misses       3383     3378       -5     
- Partials      138      180      +42     

Components	Coverage Δ
palette	82.68% <81.59%> (+0.01%)	⬆️
palette_derive	81.98% <ø> (ø)