Overhaul style and formatting

[Spartan322]

Add pre-commit configuration file
Organize and overhaul .clang-format
Add codespell checks and corrections

[Hop311]

There are a lot of good catches here, particularly spelling mistakes, but in many places clang-format is still very messy and inconsistent IMO, especially with newlines and indentation. If we can find settings that address these issues that would be great, but in its current state I find it makes the code harder to read overall and I wouldn't want it applied everywhere automatically.

Thinking about it some more, if we could disable it from doing anything about indentation/newlines (particularly in relation to brackets) that would solve most of its problems. Most formatting issues I see in PRs are to do with stuff like missing single spaces while indentation tends to be good (as it's far more obvious when it's badly wrong).