This is a step towards user-visible actions

Inferred flags can make it hard for a future action to trigger behavior
off of the selected alias, like we might want to do for negations, so we
are now translating to the intended arg.

This will also help for debugging.

We were independently starting occurrences and starting value groups.
Now we do them at the same time.

COMPATIBILITY: This changes us from counting occurrences per positional
when using `multiple_values` to one occurrence.  This is user visible
and tests were written against it but it goes against the documentation
and doesn't quite make sense.

Fixes clap-rs#3761

Doesn't make sense to respect how the command line ended

I wrote these tests expecting to highlight a bug but it turns out things
were structured just right to not exhibit it.  The fact that the code
looks like its broken is a problem, so I restructured it (put it first,
changed the source) so it doesn't look suspicious anymore.

Before, if we were in trailing values that aren't delimite, we wouldn't
respect this flag and end processing of the value, now we do.

This also has a slight perf benefit of us only splitting the value if
the delimiter is present.  We checked for the delimiter anyways, so
doing it first removes a slight bit of work.

I also feel this helps clarify the intended behavior and ooches us
towards a unified code path for actions.

Especially important is not inferring intent from occurrences as
hopefully that will change with the introduction of actions.