Add experimental structured CLI output

[Przemysław Kłys (PrzemyslawKlys)]

Description

Experimental structured output for installed-package and available-upgrade listings, behind the structuredOutput setting. The published implementation targets the earlier version of #6534.

This remains a draft until the revised specification is agreed. The contract revision in #6534 changes the shared invocation envelope, package/source/version relationships, invocation errors, diagnostic identifiers, and default JSON formatting. Those changes are not implemented by the current head of this PR.

Once the contract is accepted, this branch needs the corresponding implementation changes, a conflict resolution against master, and fresh command/schema validation. It currently includes the earlier specification commits because GitHub cannot use a fork-only branch as the base of a PR into this repository; the final diff should contain only the implementation after #6534 lands.

AI assistance: OpenAI Codex assisted with the implementation and this revision assessment.

References

• Depends on Spec: structured output for WinGet CLI #6534
• Related to JSON Formatted Output Support #184
• Add JSON format for list outputs #6346 is the older implementation and can be retired after the replacement direction is accepted

Validation

The earlier command and schema tests cover the existing implementation. They do not qualify it against the revised specification. AppInstallerCLITests, structured-output behavior tests, text-output regressions, and schema validation must be rerun after the contract changes are implemented.

Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Specification agreed
• Implementation updated to the agreed contract
• Conflicts resolved and validation rerun

Issue Type

• Bug fix
• Feature
• Task

Microsoft Reviewers: Open in CodeFlow

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