Automatically generate Context boilerplate for driver callbacks

[xFrednet]

Adding a new driver callback currently includes changes in several files with a few type conversions. This always adds some friction for simple changes. Ideally, I'd like a way to generate this boilerplate code with all the type conversion. This would make the interface a bit safer, help with implementations and reviews.

I think it would be better to generate the code with a tool and automatically replace it in the file. Similar to how cargo dev update_lints works in Clippy. Derive macros can sometimes be a bit iffy with IDEs and harder to debug. But I'm open to suggestions :)

See #121 for an example, of what boilerplate is needed