The end year is legally and functionally redundant, and more importantly causes
cherry-pick conflicts when trying to maintain old branches. Use git for history.
This allows end-users testing a specific plugin to start fwupd with an extra
command line parameter, e.g. `--plugin-verbose=unifying` to output a lot of
debugging information to the console for that specific plugin.
This replaces a lot of ad-hoc environment variables with different naming
conventions.
