Generate Lua sourcemaps for debugging

[SHiLLySiT]

The VSCode extension local-lua-debugger-vscode can be used to debug Playbit games. However, only the final Lua files can be debugged, not the original source Lua files. For the most part this isn't an issue, but it would be nice to have support for setting breakpoints in source files, especially for complex build pipelines.

To support debugging source files, Playbit needs to generate sourcemaps.

Playbit relies on the external tool LuaPreprocess to do the processing, however it doesn't support generating sourcemap files. So to accomplish this, we'll likely need to add the functionality directly into LuaPreprocess.