Categorise arguments to ensure user-specified ones take precedence
over values set by the launcher.
When any positional arg is set, exclude all positional ones from being
set at all, to prevent strange interactions.
Display a warning when the user tries to set arguments in additional
settings which the launcher will also set / conflict with. Blacklist
is still evolving, and we don’t actually prevent the user from running,
since maybe they are doing something special
