requesting a previously undeclared key is most likely an programming
error. e.g. a typo "--unused vs --unsued".
So throw in those cases.

Add an according failure testcase.

And refactor the code to make sure that the dev and runtime package lists are
in sync.

Because that's the variable actually used by CPack.

fix position of assert expected/actual parameter

`has()` only tests for an argument presence which is always true for
arguments with default values. Use `get<bool>()` to check the value
instead.

and not consider its value. treat arguments with a set default value as
present.