Perf | various performance improvements for SqlDataReader, TdsParser, SqlGuid and SqlBinary

[wilbit]

I was working on boxing of SqlBinary particularly, but found more kinda related issues.
The PR fixes:

• boxing of SqlBinary struct;
• copying of SqlBinary's internal array of bytes back and forth;
• creating of empty arrays for null values in SqlDataReader;
• copying of an array of bytes for SqlGuid.

[Wraith2]

For changes like avoiding the SqlBinary getter consider exceptions. For example, if that code path end up with the wrong data in the buffer, a string or something else, and you request the SqlBinary value currently it's going to throw an InvalidCastException, will your changed code path do the same? Because it's a very old library any externally visible behaviour change is going to break some code somewhere.

[Wraith2]

This may not be safe because unencryptedBytes is a parameter so you will need to audit all the callsites to make sure that ownership is always relinquished by the callers.

[codecov]

Codecov Report

Attention: Patch coverage is 64.70588% with 12 lines in your changes missing coverage. Please review.

Project coverage is 56.87%. Comparing base (900d051) to head (f856e2b).
Report is 189 commits behind head on main.

Files with missing lines	Patch %	Lines
...qlClient/src/Microsoft/Data/SqlClient/SqlBuffer.cs	66.66%	4 Missing ⚠️
...rosoft/Data/SqlTypes/SqlTypeWorkarounds.netcore.cs	0.00%	3 Missing ⚠️
.../netcore/src/Microsoft/Data/SqlClient/TdsParser.cs	66.66%	2 Missing ⚠️
...osoft/Data/SqlClient/Server/ValueUtilsSmi.netfx.cs	0.00%	2 Missing ⚠️
...nt/netfx/src/Microsoft/Data/SqlClient/TdsParser.cs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2308       +/-   ##
===========================================
- Coverage   72.49%   56.87%   -15.63%     
===========================================
  Files         310      304        -6     
  Lines       61868    61557      -311     
===========================================
- Hits        44854    35009     -9845     
- Misses      17014    26548     +9534     

Flag	Coverage Δ
addons	∅ <ø> (∅)
netcore	59.62% <60.86%> (-17.08%)	⬇️
netfx	54.35% <69.56%> (-15.59%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[wilbit]

Thanks for the feedback, @Wraith2 , I will consider that.

[cheenamalhotra]

Closed PR since it's been inactive for more than a month and is not ready to be reviewed.