Add GHZ fidelity tool

[eliottrosenberg]

A tool for measuring the fidelity of GHZ states.

Utilizes the pauli_string_measurement_with_readout_mitigation tool by @ddddddanni. FYI @shashwatk1998

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.63%. Comparing base (9dc6526) to head (ee77bed).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7944   +/-   ##
=======================================
  Coverage   99.63%   99.63%           
=======================================
  Files        1108     1110    +2     
  Lines       99584    99662   +78     
=======================================
+ Hits        99218    99296   +78     
  Misses        366      366           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[pavoljuhas]

I have a couple of small comments I'd like to address before the merge, otherwise LGTM.

Thank you for adding this and for rearranging the ghz code!

PS: I also pushed in a tiny tweak to type annotations.

[pavoljuhas]

LGTM after speeding up the test