Make `CommutingEvolution` a `SymbolicOp`

[dwierichs]

Context: CommutingEvolution has the structure of a ScalarSymbolicOp, so we make it one.

Description of the Change: Change base class of CommutingEvolution and adapt other attributes of the class to this change.

In addition, a dispatch branch of qml.equal for all ScalarSymbolicOps is introduced.

Benefits: Code quality

Possible Drawbacks:

Related GitHub Issues:

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.67%. Comparing base (5b81a8a) to head (5b6da65). Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5682      +/-   ##
==========================================
- Coverage   99.68%   99.67%   -0.01%     
==========================================
  Files         415      415              
  Lines       38886    38602     -284     
==========================================
- Hits        38762    38477     -285     
- Misses        124      125       +1     

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[trbromley]

@dwierichs? Do we have a story for this PR? If so, please could you link? It makes it easier to track where things sit in the roadmap.

[dwierichs]

@trbromley I don't think we have a story, because this PR came out of exploratory work for [sc-61425]. I don't know whether we are still interested in making this one happen?