Add tests for xDSL conversion and inlining utilities

[mudit2812]

This PR adds testing for the utilities defined in pennylane.compiler.python_compiler.conversion.

[sc-103169]

[github-actions]

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Please edit doc/releases/changelog-dev.md with:

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (xdsl-coverage@d45c836). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             xdsl-coverage    #8610   +/-   ##
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  Coverage                 ?   99.24%           
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  Files                    ?      635           
  Lines                    ?    65262           
  Branches                 ?        0           
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  Hits                     ?    64767           
  Misses                   ?      495           
  Partials                 ?        0           

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