[7.0.1 Cherry-pick] Extract SqlBulkCopy column names using dynamic SQL

[github-actions]

Cherry-pick of #4092 (1ec7675) into release/7.0.

Note: Milestone 7.0.1 does not exist yet. Please create it and assign this PR manually.

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[codecov]

Codecov Report

❌ Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.55%. Comparing base (864f666) to head (1b61cbb).
⚠️ Report is 3 commits behind head on release/7.0.

Files with missing lines	Patch %	Lines
...Client/src/Microsoft/Data/SqlClient/SqlBulkCopy.cs	63.63%	4 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (864f666) and HEAD (1b61cbb). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (864f666)	HEAD (1b61cbb)
CI-SqlClient	1	0

Additional details and impacted files

@@               Coverage Diff               @@
##           release/7.0    #4147      +/-   ##
===============================================
- Coverage        73.07%   65.55%   -7.53%     
===============================================
  Files              280      275       -5     
  Lines            42997    65825   +22828     
===============================================
+ Hits             31422    43154   +11732     
- Misses           11575    22671   +11096     

Flag	Coverage Δ
CI-SqlClient	?
PR-SqlClient-Project	65.55% <63.63%> (?)

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.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.