Enable checks that require code cleanup in .clang-tidy

To enable it, remove it from the list of committed checks.

These checks are nice to have, but are current code does not conform to them. We need to cleanup the existing code first.

Checks to enable:
- [ ] bugprone-unused-return-value
- [ ] bugprone-inc-dec-in-condition
- [ ] bugprone-unused-local-non-trivial-variable
- [ ] misc-include-cleaner: too many *true* positives. We need to clean up the code, but we should do that over time, maybe per-directory, instead of blocking the adoption of Clang 17 until it is all fixed.

Start by reviewing the committed-check list in .clang-tidy and the four checks named in the issue. Inspect existing violations across the codebase, clean them up incrementally, and consider directory-level progress for misc-include-cleaner; done means the listed checks can be enabled without the current code violations.

索引モデルが issue の本文から書いたものです。