Expose SSPI context provider as public

[twsouthwick]

Important

Stacked against #2454. Opened as a draft to enable validation, but since this is on a separate fork, GitHub does not support stacked PRs natively AFAIK

This change:

• Adds a property to SqlConnection to allow setting a provider
• Plumbs that property into the TdsParser so that it can be used if set

Fixes #2253

[codecov]

Codecov Report

Attention: Patch coverage is 78.31325% with 18 lines in your changes missing coverage. Please review.

Project coverage is 66.17%. Comparing base (9450fde) to head (cfcf164).

Files with missing lines	Patch %	Lines
...core/src/Microsoft/Data/SqlClient/SqlConnection.cs	61.53%	5 Missing ⚠️
...etfx/src/Microsoft/Data/SqlClient/SqlConnection.cs	54.54%	5 Missing ⚠️
...crosoft/Data/SqlClient/SSPI/SSPIContextProvider.cs	83.87%	5 Missing ⚠️
...t/Data/SqlClient/SSPI/NativeSSPIContextProvider.cs	66.66%	1 Missing ⚠️
...ata/SqlClient/SSPI/NegotiateSSPIContextProvider.cs	87.50%	1 Missing ⚠️
...c/Microsoft/Data/SqlClient/SqlConnectionPoolKey.cs	87.50%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (9450fde) and HEAD (cfcf164). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (9450fde)	HEAD (cfcf164)
addons	1	0

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2494      +/-   ##
==========================================
- Coverage   72.76%   66.17%   -6.59%     
==========================================
  Files         287      281       -6     
  Lines       59173    58892     -281     
==========================================
- Hits        43055    38973    -4082     
- Misses      16118    19919    +3801     

Flag	Coverage Δ
addons	?
netcore	69.14% <75.75%> (-6.32%)	⬇️
netfx	64.85% <67.27%> (-6.27%)	⬇️

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[nhart12]

Suggested change

	protected abstract void GenerateSspiClientContext(System.ReadOnlySpan<byte> incomingBlob, System.Buffers.IBufferWriter<byte> outgoingBlobWriter, SqlAuthenticationParameters authParams);
	protected abstract bool GenerateSspiClientContext(System.ReadOnlySpan<byte> incomingBlob, System.Buffers.IBufferWriter<byte> outgoingBlobWriter, SqlAuthenticationParameters authParams);

[nhart12]

Suggested change

	protected abstract void GenerateSspiClientContext(System.ReadOnlySpan<byte> incomingBlob, System.Buffers.IBufferWriter<byte> outgoingBlobWriter, SqlAuthenticationParameters authParams);
	protected abstract bool GenerateSspiClientContext(System.ReadOnlySpan<byte> incomingBlob, System.Buffers.IBufferWriter<byte> outgoingBlobWriter, SqlAuthenticationParameters authParams);