feat: add structured JSON/YAML output for list commands

[arvindk-softwaredev]

Part of #2850

Changes

Adds -o json and -o yaml to list commands so users can get machine-readable output instead of only the table view.

Supported resources:

• Pipeline, Task, PipelineRun, TaskRun
• EventListener, TriggerBinding, ClusterTriggerBinding, TriggerTemplate
• CustomRun

JSON/YAML is an array of resource objects, not a Kubernetes List wrapper. Each item includes canonical apiVersion and kind. Empty results print [] / []. Invalid formats are rejected with an error. Default table output is unchanged.

Shared helpers live in pkg/formatted (PrintStructuredOutput, SetTypeMeta, IsStructured). Help text, generated docs, and man pages are updated. Unit tests cover structured output, empty lists, invalid formats, and help examples.

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes tests (if functionality changed/added)
• Run the code checkers with make check
• Regenerate the manpages, docs and go formatting with make generated
• Commit messages follow commit message best practices

See the contribution guide
for more details.

Release Notes

Add -o json and -o yaml support to list commands for pipelines, tasks, pipeline runs, task runs, event listeners, trigger bindings, cluster trigger bindings, trigger templates, and custom runs. Structured output is an array of resource objects (not a Kubernetes List wrapper).

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[Copilot]

🟡 Changes recommended

Structured serialization bypasses the advertised managed-fields filtering behavior.

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Pull request overview

Adds machine-readable JSON/YAML array output to nine Tekton resource list commands while retaining table output.

Changes:

• Adds shared structured-output and TypeMeta helpers.
• Integrates array output across Pipeline, Task, run, trigger, and CustomRun commands.
• Updates tests, golden files, command docs, and man pages.

File summaries

File	Description
test/e2e/pipeline/pipeline_test.go	Validates Pipeline JSON arrays.
pkg/formatted/output.go	Adds structured-output helpers.
pkg/formatted/output_test.go	Tests shared helpers.
pkg/cmd/triggertemplate/list.go	Adds TriggerTemplate arrays.
pkg/cmd/triggertemplate/list_test.go	Tests TriggerTemplate output.
pkg/cmd/triggerbinding/list.go	Adds TriggerBinding arrays.
pkg/cmd/triggerbinding/list_test.go	Tests TriggerBinding output.
pkg/cmd/taskrun/list.go	Adds TaskRun arrays.
pkg/cmd/taskrun/list_test.go	Tests TaskRun output.
pkg/cmd/task/testdata/TestTaskList_in_all_namespaces_with_output_yaml_flag.golden	Updates Task YAML fixture.
pkg/cmd/task/list.go	Adds Task arrays and examples.
pkg/cmd/task/list_test.go	Tests Task output.
pkg/cmd/pipelinerun/list.go	Adds PipelineRun arrays.
pkg/cmd/pipelinerun/list_test.go	Tests PipelineRun output.
pkg/cmd/pipeline/testdata/TestPipelineList_output_json.golden	Adds Pipeline JSON fixture.
pkg/cmd/pipeline/testdata/TestPipelineList_in_all_namespaces_with_output_yaml_flag.golden	Updates Pipeline YAML fixture.
pkg/cmd/pipeline/list.go	Adds Pipeline arrays and examples.
pkg/cmd/pipeline/list_test.go	Tests Pipeline output.
pkg/cmd/eventlistener/list.go	Adds EventListener arrays.
pkg/cmd/eventlistener/list_test.go	Tests EventListener output.
pkg/cmd/customrun/list.go	Adds CustomRun arrays.
pkg/cmd/customrun/list_test.go	Tests CustomRun output.
pkg/cmd/clustertriggerbinding/list.go	Adds cluster binding arrays.
pkg/cmd/clustertriggerbinding/list_test.go	Tests cluster binding output.
docs/man/man1/tkn-triggertemplate-list.1	Documents structured examples.
docs/man/man1/tkn-triggerbinding-list.1	Documents structured examples.
docs/man/man1/tkn-taskrun-list.1	Documents structured examples.
docs/man/man1/tkn-task-list.1	Documents structured examples.
docs/man/man1/tkn-pipelinerun-list.1	Documents structured examples.
docs/man/man1/tkn-pipeline-list.1	Documents structured examples.
docs/man/man1/tkn-eventlistener-list.1	Documents structured examples.
docs/man/man1/tkn-customrun-list.1	Documents structured examples.
docs/man/man1/tkn-clustertriggerbinding-list.1	Documents structured examples.
docs/cmd/tkn_triggertemplate_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_triggerbinding_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_taskrun_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_task_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_pipelinerun_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_pipeline_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_eventlistener_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_customrun_list.md	Adds JSON/YAML examples.
docs/cmd/tkn_clustertriggerbinding_list.md	Adds JSON/YAML examples.

Review details

• Files reviewed: 42/42 changed files
• Comments generated: 1
• Review effort level: Balanced

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