Prior to this commit, the `SimpleCommandLineArgsParser` would reject
"--" arguments as invalid. As reported by the community, the POSIX
utility conventions (Guideline 10) state that
> The first -- argument that is not an option-argument should be
> accepted as a delimiter indicating the end of options.
> Any following arguments should be treated as operands, even if they
> begin with the '-' character.
This commit updates `SimpleCommandLineArgsParser` to not reject "--"
arguments and instead to consider remaining arguments as non-optional.
See gh-31513
b4131ce131