Revert "Be more careful to maintain quoting information when parsing commands."

This reverts commit 6c089b2a.

This was causing the test test_help_run_hides_options from TestHelp.py to
fail on Linux and Windows (but the test succeeds on macOS).  The decision
to print option information is determined by CommandObjectAlias::IsDashDashCommand
which was changed, but only by replacing an inline string constant with a const char *
CommandInterpreter::g_argument which has the same string value.  I can't see why this
would fail, I'll have to spin up a vm to see if I can repo there.