Use ThreadStatic fields over LocalDataStoreSlot for improved performance

[h3xds1nz]

Description

Replaces LocalDataStoreSlot with [ThreadStatic] fields for improved performance and increased type safety.

• Static cost of initializing a LocalDataStoreSlot is about 500 ns and 184 B, that will forever live.
• The retrieval process using Thread.GetData is about 40% more expensive.
• There is no reason to use LocalDataStoreSlot these days (though it uses ThreadLocal<object?> under the hood since .NET Core 3.0 afaik so the performance is not THAT bad, while NetFX still goes with the original impl).

In the other commits, I've just cleaned up some CAS remnants (Critical/Unsecure methods/properties) from ComponentDispatcher, that just unnecessarily complicate the code these days. Since the formatting was different style on each, I've unified that.

10 property retrievals before/after (already initialized)

Method	Mean [ns]	Error [ns]	StdDev [ns]	Code Size [B]	Allocated [B]
Original	25.15 ns	0.061 ns	0.054 ns	334 B	-
PR_EDIT	14.07 ns	0.157 ns	0.139 ns	130 B	-

Customer Impact

Improved performance, increased code base quality and type safety for developers.

Regression

No.

Testing

Local build, sample app run and testing with all the modified types.

Risk

Low.

Microsoft Reviewers: Open in CodeFlow

[h3xds1nz]

Rebased and resolved merge conflicts.

[codecov]

Codecov Report

Attention: Patch coverage is 48.27586% with 30 lines in your changes missing coverage. Please review.

Project coverage is 10.90597%. Comparing base (2ded801) to head (5f642cb).
Report is 4 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main       #9959         +/-   ##
===================================================
- Coverage   10.95887%   10.90597%   -0.05290%     
===================================================
  Files           3310        3310                 
  Lines         664667      664297        -370     
  Branches       74667       74664          -3     
===================================================
- Hits           72840       72448        -392     
- Misses        590685      590717         +32     
+ Partials        1142        1132         -10     

Flag	Coverage Δ
Debug	10.90597% <48.27586%> (-0.05290%)	⬇️

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