Make sure that everything is Clang formatted

[Jayman2000]

Pull Request Type

• [x] GitHub Workflow changes
• [ ] Documentation or Wiki changes
• [ ] Build and Dependency changes
• [ ] Runtime changes
  • [ ] Render changes
  • [ ] Audio changes
  • [ ] Input changes
  • [ ] Network changes
  • [ ] Other changes

Description

This PR does multiple clang-format related things:

1. It revamps tools/formatter.sh.

2. It fixes and re-enables the clang-format workflow.

3. It makes sure that all files obey the style settings in .clang-format.

Related Issues

Closes #450.

Checklist

• [x] I have tested my changes locally and verified that they work as intended.
• [ ] I have documented any new or modified functionality.
• [x] I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• [x] I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

Additional Comments

This PR is meant to be an alternative to #450. Here are the differences between this PR and that other PR.

• The script that this PR introduces is much shorter than the two scripts that other PR introduces.
• The script that this PR introduces has less dependencies that the shell script that the other PR introduces. This PR’s script depends on /bin/sh, git and clang-format. The other PR’s shell script depends on /bin/sh, which, clang-format, xargs/parallel and find.
• The script that this PR introduces does not depend on which. The shell script that the other PR introduces depends on a version of which that support the -s flag. GNU which does not support the -s flag.. I don’t know how common GNU which is compared to other implementations of which, but I do know that GNU which is a required package on NixOS and a mandatory package on Fedora Workstation.
• The script that this PR introduces doesn’t bother checking whether or not its dependencies are present before trying to execute them. The shell script that the other PR introduces checks for its dependencies before trying to execute them. As far as I know, there’s no real consequences if this PR’s script gets run by someone who doesn’t have git or clang-format, so checking to see if they’re available is not necessary.
• This PR introduce a single shell script. The other PR introduces a shell script and a batch script. Windows users can just run the shell script in Git Bash. After all, building Descent 3 already depends on Git, and Git depends on “A POSIX-compliant shell”.

[!IMPORTANT]
I’m not so sure that this PR should actually be merged. I have a concern that I wrote about here. Depending on how we decide to resolve that concern, I might end up canceling this PR.