Add clang-format v17.0.6 install guide to C++ README

[HTHou]

Summary

• Document the clang-format v17.0.6 requirement used by mvn spotless
• Add macOS and Windows install commands plus version verification
• Show the spotless:apply command and a spotless.skip example

Testing

• Not run (not requested)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.75%. Comparing base (2ab087b) to head (a30a65f).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #786   +/-   ##
========================================
  Coverage    62.75%   62.75%           
========================================
  Files          706      706           
  Lines        42836    42836           
  Branches      6324     6324           
========================================
+ Hits         26881    26882    +1     
  Misses       14963    14963           
+ Partials       992      991    -1     

☔ 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.