Clang-format sees the text behind `#pragma region` as code and formats it. Instead of stating the copyright and date there, it's now in the comment block right below it. The text "Copyright" is left in the `#pragma region` line, as clang-format sees it as a single identifier.
I took the opportunity to normalize the dates, and add the copyright notice to the source files where it was missing them (except for third-party and the generated resources.h file).
By using a dummy audio context, we can now make openrct2-cli start a headless instance without any SDL2 calls. SDL2 is still a dependency until we remove out the input code to openrct2-ui.
