pkg/domain: return an error instead of nil on remote event parse failure

[ROKUMATE]

What

In remote mode, podman events --format json could print the literal null
instead of an event object. ConvertToLibpodEvent returned nil on a parse
failure and the tunnel forwarded it as an event with no error set, so the nil
event was marshalled to null.

This returns an error from ConvertToLibpodEvent and sends it on the event
channel (which the CLI already handles) instead of a nil event.

Test

pkg/domain/entities/events_test.go: a valid event converts correctly, and
unknown status, unknown type, and an invalid containerExitCode each return an
error instead of nil.

Checklist

• Certify you wrote the patch ... (git commit -s)
• Referenced issues (not completely fixes podman events --format json returns null via remote api #28325)
• Tests have been added/updated
• Documentation ... (no docs needed)
• All commits pass make validatepr
• Release note entered below

Does this PR introduce a user-facing change?

thepodman events --format json cmd no longer prints null when a server event can't be parsed ... it returns an error instead

[danishprakash]

Please refer to main/CONTRIBUTING.md main/LLM_POLICY.md.

And also it'd be helpful if you could follow the PR template for the description.

[ROKUMATE]

@danishprakash i read it i added the checklist for now
and hanceforth in next pr wont use it for writting the pr description and all 👍🏼
any point i missed in the fix u would like me to check on ??

[packit-as-a-service]

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