Caching SQLServerBulkCopy object for batch insert

[tkyc]

If bulkcopy is used for batch insert, and if multiple executeBatch() calls are made against the same prepared statement, then multiple SQLServerBulkCopy objects are instantiated which will cause repeated calls to select * sys.columns.... This PR caches the SQLServerBulkCopy object.

[codecov]

Codecov Report

Attention: Patch coverage is 62.96296% with 20 lines in your changes missing coverage. Please review.

Project coverage is 50.77%. Comparing base (722c910) to head (edf02ce).
Report is 2 commits behind head on main.

❗ Current head edf02ce differs from pull request most recent head 76479d5

Please upload reports for the commit 76479d5 to get more accurate results.

Files	Patch %	Lines
...oft/sqlserver/jdbc/SQLServerPreparedStatement.java	62.26%	11 Missing and 9 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2435      +/-   ##
============================================
+ Coverage     50.13%   50.77%   +0.64%     
- Complexity     3842     3880      +38     
============================================
  Files           145      145              
  Lines         33409    33421      +12     
  Branches       5667     5676       +9     
============================================
+ Hits          16750    16970     +220     
+ Misses        14258    14006     -252     
- Partials       2401     2445      +44     

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

[lilgreenbird]

add test

Test has been added.