Change use of measurements to records in tomography [continued]

[kerryzhou1024]

Bringing PR #7421 across the finish line since the original contributors' internships have concluded. I can't edit the original PR, so forking and opening another PR would be the most efficient.

In the file qubit_characterizations.py, in the function definition of single_qubit_state_tomography, changing the use of measurements to records allows for circuits with multiple key measurements to be supported without throwing an error for having repeated keys

Heavy lifting by
@kygnz
@sgavi4
@abyssaldragonz
@thomasasha

Closes issue #7417 and the original PR #7421

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.53%. Comparing base (cd32133) to head (9b318e9).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7477      +/-   ##
==========================================
- Coverage   97.53%   97.53%   -0.01%     
==========================================
  Files        1095     1095              
  Lines       99002    99016      +14     
==========================================
+ Hits        96566    96576      +10     
- Misses       2436     2440       +4     

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[vtomole]

LGTM

[vtomole]

Merging after @maffoo approves.

[kerryzhou1024]

Tested the snippet locally and it passed for me!