Extract common base cursor wrapper class

[jayaddison]

This change follows on from #1475 and introduces a common base class for cursor wrappers.

This base class is substituted in to the conditional check that identifies whether a cursor is already wrapped by DDT's SQL cursor tracking.

This should be compatible with the test coverage offered in #1478.

[codecov]

Codecov Report

Merging #1479 (eee102e) into main (6ec6bfe) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1479      +/-   ##
==========================================
+ Coverage   86.26%   86.27%   +0.01%     
==========================================
  Files          35       35              
  Lines        1856     1858       +2     
  Branches      261      261              
==========================================
+ Hits         1601     1603       +2     
  Misses        182      182              
  Partials       73       73              

Impacted Files	Coverage Δ
debug_toolbar/panels/sql/tracking.py	88.23% <100.00%> (+0.20%)	⬆️

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[matthiask]

Thanks!

[jayaddison]

Thank you!