[DOP-19024] Fix passing custom JDBC options to Greenplum.extra

[dolfinus]

Change Summary

Add options passed to Greenplum(extra={"some": "value"}) to JDBC URL query part.
Add unit tests.

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.40%. Comparing base (c6b09be) to head (6c4e8da).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #308      +/-   ##
===========================================
+ Coverage    95.25%   95.40%   +0.15%     
===========================================
  Files          225      225              
  Lines         8940     8949       +9     
  Branches      1516     1518       +2     
===========================================
+ Hits          8516     8538      +22     
+ Misses         302      290      -12     
+ Partials       122      121       -1     

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