Integrate CliffordBackend and stim

[renatomello]

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.95%. Comparing base (d559a61) to head (07291f5).

Additional details and impacted files

@@             Coverage Diff             @@
##            master    #1248      +/-   ##
===========================================
- Coverage   100.00%   99.95%   -0.05%     
===========================================
  Files           72       72              
  Lines        10440    10452      +12     
===========================================
+ Hits         10440    10447       +7     
- Misses           0        5       +5     

Flag	Coverage Δ
unittests	99.95% <100.00%> (-0.05%)	⬇️

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[alecandido]

It should be alright, just a few comments to polish and improve readability.

[BrunoLiegiBastonLiegi]

Thanks @renatomello looks good. There is just one thing that is missing in my opinion, which is in the Clifford object let stim take care of the samples generation.

[renatomello]

Thanks @renatomello looks good. There is just one thing that is missing in my opinion, which is in the Clifford object let stim take care of the samples generation.

There is a way to do it, but it's not as direct as the circuit execution, so maybe it'd be better to do it in a separate PR.