Improve the shell completion api

[Luap99]

One main advantage of the new shell completion logic is that
we can easly parse flags and adjust based on the given flags
the suggestions. For example some commands accept the
--latest flag only if no arguments are given.

This commit implements this logic in a simple maintainable way
since it reuses the already existing Args function in the
cmd struct.

I also refactored the getXXX function to match based on the
namei/id which could speed up the shell completion with many
containers, images, etc...

I also added the degraded status to the valid pod status
filters which was implemented in #8081.

[Luap99]

Basically typing podman start --latest [TAB] won't recommend container names while podman start [TAB] does.
This applies to all command which are using a Args function.

[rhatdan]

LGTM
/approve

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[rhatdan]

@edsantiago PTAL
@containers/podman-maintainers PTAL

[Luap99]

I pushed a small update to handle the ExactArgs(2) or MinimumNArgs(2) functions correct. Otherwise podman cp [TAB] would have failed.

[edsantiago]

The refactoring LGTM - I'm finding situations where it doesn't work as I expected (podman top, podman container inspect -l) but it's still sooooo much better than what we had before. This can be refined over time. Thanks for your initiative in taking this on.

Two very minor suggestions, left up to your discretion.

[Luap99]

@edsantiago Updated. My error parsing didn't really work as expected. I have to clean the differences in the error message first. I thought %s could handle that.

[Luap99]

Not all commands use a meaningful Args function. e.g. podman top

I have to go through them one by one to see were I can improve this.

[edsantiago]

Yes, that makes sense, and it can be fixed over time. No rush, this is already very helpful.

[edsantiago]

The tight coupling to (and massaging of) cobra messages bothers me a little, but I can't think of a better way to do it. On the whole this LGTM but I'd like confirmation review from at least one more @containers/podman-maintainers team member.

[rhatdan]

/lgtm