Remove KnownColors static constructor

[ThomasGoulet73]

Description

Removes KnownColors static constructor and replaces it with uint parsing and calling Enum.IsDefined. The static constructor is called at the startup of every WPF app AFAIK (It is called even with an app created from the empty WPF template). The size of the dictionary at runtime is about 10 Kb so not much but it is still unnecessary used memory.

Benchmark results of KnownColors.ArgbStringToKnownColor

Method	argbString	Mean	Error	StdDev	Ratio	RatioSD	Allocated	Alloc Ratio
Old	#FFDA70D6	15.2223 ns	0.2156 ns	0.2017 ns	1.00	0.02	-	NA
New	#FFDA70D6	13.6033 ns	0.0437 ns	0.0365 ns	0.89	0.01	-	NA
Old	#XYZ	9.1676 ns	0.0399 ns	0.0353 ns	1.00	0.01	-	NA
New	#XYZ	5.4110 ns	0.0116 ns	0.0097 ns	0.59	0.00	-	NA
Old	FFDA70D6	11.5086 ns	0.0509 ns	0.0476 ns	1.00	0.01	-	NA
New	FFDA70D6	0.8499 ns	0.0034 ns	0.0028 ns	0.07	0.00	-	NA

Customer Impact

Better perf, better startup perf and lower static memory.

Regression

No.

Testing

Local testing.

Risk

Low.

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