machine: Add -all-providers flag to machine list

[ashley-cui]

Podman machine list now supports a new option, --all-providers, which lists all machines from all providers.

Does this PR introduce a user-facing change?

Podman machine list now supports a new option, --all-providers, which lists all machines from all providers.

[ashley-cui]

Unclear that the test will go through on Windows, since we WSL and HyperV don't share images, but I'm not on Windows today, so I'm throwing it at CI and hoping. Mac passed locally though.

[Luap99]

Shouldn't there be at least a field in the list output that shows the user which provider the VM uses?

[ashley-cui]

@Luap99 List already has a field for provider :)

[Luap99]

@Luap99 List already has a field for provider :)

oops yes, I somehow looked for a provider field but it is called VM TYPE

[ashley-cui]

@containers/podman-maintainers @jakecorrenti @Luap99 @baude PTAL, TY!

[ashley-cui]

@containers/podman-maintainers PTAL

[mheon]

Code LGTM

[Luap99]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ashley-cui, Luap99

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