feat: add structured JSON/YAML output for delete command

[ankrsinha]

Part of #2850

Changes

Add --output json/yaml (-o) structured output support for delete
command (by name, without bulk flags) across 8 resource types:
task, pipeline, pipelinerun, customrun, eventlistener, triggerbinding,
triggertemplate, and clustertriggerbinding.

TaskRun is excluded (covered by #3086).

When used, the result is returned as machine-readable output

Example:

$ tkn task delete foo bar -n ns -o json
{
    "deleted": [
        "foo",
        "bar"
    ]
} 

$ tkn task delete foo -n ns -o yaml
deleted:
- foo

• Output structure is the same for all resources.
• Bulk delete with flags like --all, --keep, --trs, --prs is
  not in scope and will be a follow-up.

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• Includes tests (if functionality changed/added)
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Release Notes

Add --output json/yaml support for delete commands across
task, pipeline, pipelinerun, customrun, eventlistener,
triggerbinding, triggertemplate, and clustertriggerbinding.

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[chmouel]

Thanks for adding structured output to delete. I found a few paths that still need attention: --all and pipelinerun delete --pipeline can print plain text with -o json or -o yaml; pipeline delete --prs and task delete --trs leave the related runs out of the result; and a later deletion error can hide resources already deleted, including CustomRuns. Could the structured result include every successful deletion, even when the command also returns an error?

[ankrsinha]

@chmouel Thanks for the review and for catching these.

--all and pipelinerun delete --pipeline can print plain text with -o json or -o yaml

This is intentional as this PR does not focus on bulk delete (with flags like --all, --pipeline, --keep). This will be handled in a seperate PR.

pipeline delete --prs and task delete --trs leave the related runs out of the result; and a later deletion error can hide resources already deleted, including CustomRuns. Could the structured result include every successful deletion, even when the command also returns an error?

Agreed on this, i will update the PR for handling these two issues.