MudColor: Add XML comments and make it serializable with STJ / NewtonsoftJson

[ScarletKuro]

Description

Fixes: #7688
Fixes: #3095

This makes it compatible only with STJ.
I know other Serializers exists like Newtonsoft.Json, YamlDotNet, and many other binary ones.
But I think think most customers are using the built in - STJ, and the issues were specifically talking about it. I think advanced user can workaround it with custom converters.

How Has This Been Tested?

New unit tests.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• The PR is submitted to the correct branch (dev).
• My code follows the code style of this project.
• I've added relevant tests.

[codecov]

Codecov Report

Attention: Patch coverage is 96.26168% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 89.78%. Comparing base (0affaa4) to head (cd8ce65).
Report is 3 commits behind head on dev.

Files	Patch %	Lines
src/MudBlazor/Utilities/MudColor.cs	96.26%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8579      +/-   ##
==========================================
+ Coverage   89.70%   89.78%   +0.07%     
==========================================
  Files         411      411              
  Lines       11817    11840      +23     
  Branches     2362     2363       +1     
==========================================
+ Hits        10600    10630      +30     
+ Misses        689      682       -7     
  Partials      528      528              

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[danielchalmers]

I really really dislike the idea of locking into one serializer. Why can't it work out of the box for all serializers? Please let me look into this more before merging

Btw I did some of that cleanup in my PRs so there will be conflicts

[ScarletKuro]

Why can't it work out of the box for all serializers?

Because MudColors is immutable, when you change something via method, it creates a new "readonly" instance.
This is especially important because it's using GetHasCode and the _valuesAsByte should not change once the instance is considered initialized, but you cannot guarantee that if the property setters won't be private or init only.

For it to make work with any serializers you need:
option 1: Make RGBA with setters and HIDE other properties, add an empty constructor, remove immutability
option 2: Make _valuesAsByte public + writable, hide everything else + empty constructor, remove immutability

only then this type will function properly and you won't have other junks in the serialized object aka HLS and APercentage. It should be either RGBA or byte representation only or string aka hex.

[ScarletKuro]

@danielchalmers I added more supports, now it supports Newtonsoft as well and others that respect ISerializable.
There is no better ways to make immutable classes to have flawless serialization.

[danielchalmers]

I added more supports, now it supports Newtonsoft as well and others that respect ISerializable.

Great, thank you.

Yeah, not ideal but I get the point. I don't think there's a nicer way of doing it. Other changes are great. Nice work
I made the same changes to the color picker tests in #8576 if you don't mind reverting that

[ScarletKuro]

I made the same changes to the color picker tests in #8576 if you don't mind reverting that

I reverted ColorPickerTests