test: migrate clang-tidy to LLVM 18

[scarf005]

Checklist

Required

• I wrote the PR title in conventional commit format.
• I ran the code formatter.
• I linked any relevant issues using github keyword syntax so it can be closed automatically.
• I have committed my changes to new branch that isn't main so it won't cause conflict when updating main branch later.

Optional

• This PR ports commits from DDA or other cataclysm forks.
  • I have attributed original authors in the commit messages adding Co-Authored-By in the commit message.
  • I have linked the URL of original PR(s) in the description.
• This is a PR that modifies build process or code organization.
  • Please document the changes in the appropriate location in the doc/ folder.
  • If documentation for this feature or process does not exist, please write it.
  • If the change alters versions of software required to build or work with the game, please document it.

Purpose of change

• improve clang-tidy CI time by only running actually affected files
• revive build: yet another C++20 migration #2341 yet yet again (LLVM 12 doens't support c++20)
• make it easier to build and run plugins locally
• closes build: migrate clang-tidy to LLVM 16 #3028

Describe the solution

please check individual commits; docs will be updated later

Describe alternatives you've considered

• stuck in c++17 forever
• changing 1 line of cpp file takes 1h 20m to lint

Testing

lit checks fail, but could investigate later

Additional context

[chaosvolt]

[scarf005]

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