build: update OSX builds to llvm clang

[FriedLongJohns]

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 is a PR that modifies build process or code organization.
  • If documentation for this feature or process does not exist, please write it.

Purpose of change

• fixes OSX builds broken after PR #5685 #5755

From what I can understand, OSX builds weren't building due to apple clang being different from normal clang.

Describe the solution

I've updated the workflow files to use llvm clang from brew (COMPILER=$(brew --prefix llvm)/bin/clang++) and install the dependencies required for building (on my Mac, at least): llvm astyle from brew and polib luaparser from pip.

A line of code in src/sol/sol.hpp around line 6759 had to be changed to make the builds work, but I won't admit to knowing what I did to fix it, because chatgpt was a very poor explainer.

Also adds osx.yml for building OSX in the same way that there exists android.yml and msys-cmake.yml.

Describe alternatives you've considered

1. Fixing the part of the code that broke OSX builds in the first place

It felt like a more complete solution to me to completely decouple builds from an osx-specific clang so that maintenance would be easier later down the line.

2. Accepting that software development does not usually happen for OSX and likely will never.

Testing

I built the game with the same commands on my computer, opened a new world, played a random character, and killed a zed with a pool cue. Worked.

Should see if the tests work OK on this PR, and if it fixes builds.
Might cause a memory leak since I've messed with c++ without knowing c++... unsure how to test for that.

[autofix-ci]

Autofix has formatted code style violation in this PR.

I edit commits locally (e.g: git, github desktop) and want to keep autofix

1. Run git pull. this will merge the automated commit into your local copy of the PR branch.
2. Continue working.

I do not want the automated commit

1. Format your code locally, then commit it.
2. Run git push --force to force push your branch. This will overwrite the automated commit on remote with your local one.
3. Continue working.

If you don't do this, your following commits will be based on the old commit, and cause MERGE CONFLICT.

[scarf005]

LGTM, please ignore the clang-tidy errors, sol.hpp should've been excluded anyways because it's meant to be included from other header