RecordException in SqlClient instrumentation

[mbakalov]

Fixes #1570.

Changes

Record exceptions as ActivityEvents in SqlClient instrumentation.

• Add unit-tests
• Changes in public API reviewed - there is a public API change! SqlClientInstrumentationOptions new public property RecordException (netcore only).
• CHANGELOG.md updated for non-trivial changes

[codecov]

Codecov Report

Merging #1592 (dc8bf40) into master (1fb7695) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1592      +/-   ##
==========================================
+ Coverage   81.76%   81.79%   +0.02%     
==========================================
  Files         245      245              
  Lines        6587     6590       +3     
==========================================
+ Hits         5386     5390       +4     
+ Misses       1201     1200       -1     

Impacted Files	Coverage Δ
...ient/Implementation/SqlClientDiagnosticListener.cs	77.94% <100.00%> (+2.18%)	⬆️
...ation.SqlClient/SqlClientInstrumentationOptions.cs	98.00% <100.00%> (+0.04%)	⬆️

[mbakalov]

This is now ready for review.

Highlights of changes:

• Added bool RecordException (default false) to the SqlClientInstrumentationOptions public API.
• Added tests for it.
• On netcore we are getting an actual exception so activity.RecordException() extension is used but on netfx we just stay it is either Microsoft.Data.SqlClient.SqlException or System.Data.SqlClient.SqlException based on the event source that EndExecute is coming from.
• CHANGELOG updated