Fix typos, grammar errors, and capitalization inconsistencies in docstrings

[Hadar01]

Fix documentation issues in cirq-core/cirq/:

1.Typos: "denity" → "density", "derteines" → "determines"
2.Grammar: "is approximately" → "is approximately", "i.a." → "i.e."
3.Capitalization: "hermitian" → "Hermitian" consistently across all files
4.Punctuation: "operation ." → "operation."
5.Possessive: "who's" → "whose"
6.Variable name in docstring: "qid_state" → "qid_shape"

No behavioral changes.

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[mhucka]

@Hadar01 Thank you for this contribution. When you get a chance, can you please follow up on the contributor license agreement (CLA) per the comment by the CLA bot?

[mhucka]

@Hadar01 There are at least a couple of other places in the code where "hermitian" is not capitalized in strings, but I don't see those cases included in this PR. This makes me think that the PR is incomplete. Can you please double-check that the capitalization changes are consistent across all the files?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.63%. Comparing base (9888067) to head (0791f57).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7989      +/-   ##
==========================================
- Coverage   99.63%   99.63%   -0.01%     
==========================================
  Files        1110     1110              
  Lines       99685    99685              
==========================================
- Hits        99318    99317       -1     
- Misses        367      368       +1     

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[pavoljuhas]

Additional issues found (not included to keep PR small): ...

Yes, please include them here.

@Hadar01 - please edit the description to remove the unnecessary LLM fluff.

The Changes section should have only the kind of typos listed, the files and line numbers are obvious from the diff. Also please remove the Testing section. This PR does not change any tests (apart from error messages) - so that section does not convey anything.

The PR description will become a commit message when merged, so it is desirable for it to be informative, brief and relevant.

[Hadar01]

@mhucka Good catch, thanks! I've searched the full codebase and added the remaining cases in the second commit. Could you check if I'm still missing any?

[Hadar01]

@mhucka @pavoljuhas Done ,updated the description and included the additional fixes (who's → whose, qid_state → qid_shape) in the third commit.