CmdPal: IDetails2 update proposal [DO NOT MERGE]

[Jiří Polášek (jiripolasek)]

Summary of the Pull Request

This is a proposal to take #50180 a little further: let IContent describe the entire Details presentation, including headers and metadata, while keeping legacy and new behavior separate.

• Keep IDetails2.GetContent() as the entry point, with the returned content defining the complete presentation and its order.
• Keep ordinary Details on the legacy path; use ContentDetails to opt into the new presentation.
• Add headers with optional subtitles, compact text, properties, links, tags, commands, and separators as content elements.
• Reuse existing content types and viewers for forms, Markdown, images, plain text, and trees.

Extra prototypes, free of charge:

• Property grid: Align property labels and values in columns when there is enough width, and stack them vertically when space is limited.
• Sections: Group content under a heading, or a separator when untitled. Support nesting and an optional limited preview with an expand/collapse control at the bottom.

Pictures? Pictures!

PR Checklist

• Closes: #xxx

• Communication: I've discussed this with core contributors already. If the work hasn't been agreed, this work might be rejected
• Tests: Added/updated and all pass
• Localization: All end-user-facing strings can be localized
• Dev docs: Added/updated
• New binaries: Added on the required places
  • JSON for signing for new binaries
  • WXS for installer for new binaries and localization folder
  • YML for CI pipeline for new test projects
  • YML for signed pipeline
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed