feat: Support SProd and CompositeOp for expval

[speller26]

Issue #, if available:
#253
Description of changes:

Testing done:

Merge Checklist

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (b154dce) to head (15012c2).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #275   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines         1242      1244    +2     
  Branches       305       302    -3     
=========================================
+ Hits          1242      1244    +2     

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[speller26]

@astralcai Feel free to check if this implementation makes sense.

[astralcai]

Since it's passing PL integration tests I say it's good.