cli: More environment detection

[cgwalters]

cli: Check for container before root

This has bootc upgrade inside a container image give a more useful error message.

At least one user reran the container as root to try it...

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cli: Check for non-ostree container too

Just on general principle.

Signed-off-by: Colin Walters [email protected]

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cli: Detect non-ostree and error out earlier

Before we even check for root, verify that we are on an ostree-booted host.

Signed-off-by: Colin Walters [email protected]

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Closes: https://github.com/containers/bootc/issues/554