Expose SSPI context provider as public

[twsouthwick]

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 73.91304% with 12 lines in your changes missing coverage. Please review.

Project coverage is 59.53%. Comparing base (b8948f2) to head (45a3228).

Files with missing lines	Patch %	Lines
...core/src/Microsoft/Data/SqlClient/SqlConnection.cs	54.54%	5 Missing ⚠️
...etfx/src/Microsoft/Data/SqlClient/SqlConnection.cs	54.54%	5 Missing ⚠️
...nt/netfx/src/Microsoft/Data/SqlClient/TdsParser.cs	0.00%	1 Missing ⚠️
...a/SqlClient/ConnectionPool/SqlConnectionPoolKey.cs	87.50%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (b8948f2) and HEAD (45a3228). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (b8948f2)	HEAD (45a3228)
addons	1	0

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2494      +/-   ##
==========================================
- Coverage   67.04%   59.53%   -7.52%     
==========================================
  Files         300      294       -6     
  Lines       65376    65088     -288     
==========================================
- Hits        43831    38748    -5083     
- Misses      21545    26340    +4795     

Flag	Coverage Δ
addons	?
netcore	62.81% <78.12%> (-9.38%)	⬇️
netfx	60.79% <68.96%> (-4.40%)	⬇️

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[benrr101]

Overall, really like the goal and implementation. Most of my comments are style related, since I'm sure my colleagues have tackled the bigger questions.

[paulmedynski]

Made an initial pass, and came up with some questions/comments.

[paulmedynski]

Factory vs instance in the netfx code, and a few questions about docs.

[nhart12]

Latest package still works for our use-case

[twsouthwick]

ping @mdaigle @paulmedynski @benrr101 @David-Engel

[mdaigle]

A few small things I'd like to see addressed. I will also leave this blocked until we complete a security review. We need to do one soon for our upcoming releases anyway.

[mdaigle]

It would be nice to find a way to test the positive case, so that we know we can successfully connect via a custom context provider.

[twsouthwick]

Yeah, I struggled to figure out how to test it even for this. The main problem with a positive case is that the implementation is wildly different between frameworks so testing it starts being difficult. My thought here was to ensure it gets plumbed through, and the existing tests ensure that once it's being called that it works correctly.

If you have ideas here, please let me know how to proceed.

[paulmedynski]

@twsouthwick - Need to resolve conflicts here, but I know @benrr101 is also working on merging the .NET and .NET Framework instances of this class, so please coordinate with him.