Fix `podman import` with non-gzip inputs

[mtrmac]

• Update c/image
• Improve the documentation

Fixes: #25593 Fixes: #18193 (which was previously only documented as unsupported) Reverts: #25465

Does this PR introduce a user-facing change?

`Podman import` supports non-gzip inputs again.

[packit-as-a-service[bot]]

[NON-BLOCKING] Packit jobs failed. @containers/packit-build please check. Everyone else, feel free to ignore.

[Luap99]

bin/podman-testing   size= 54898392  delta=219688
***************************************************************************
* bin/podman-testing grew by 219688 bytes; max allowed is 51200.
*
* Please investigate, and fix if possible.
*
* A repo admin can override by setting the bloat_approved label
***************************************************************************

We should likely exclude podman-testing from the check, it is not important for the size. Podman is actually down in this vendor update.

[mtrmac]

We should likely exclude podman-testing from the check, it is not important for the size.

Added a commit to do that.

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Luap99, mtrmac

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[baude]

/lgtm