Add support for hidden files in documentation TOC

[Mpdreamz]

Hidden files can now be excluded from navigation and indexing but still linked directly if needed. Adjustments include handling hidden attributes in TOC parsing and ensuring related navigation logic respects these exclusions.

Hidden pages can be included just as you would any file in the TOC.

   hidden: my-page.md

• Still only one place to configure files.
• Participates in dangling documentation detection
• Is picked up as a MarkdownFile in our codebase like any other.
• Includes a hidden flag so that we:
  • Never render it in any navigation item.
  • Always include a noindex header.
  • Advertise it as hidden in links.json artifact.

hiddenpages.mp4

[shainaraskas]

!! NICE!

if I want to hide multiple files in the same TOC, do I need individual hidden entries, or does it accept an array? either works just interested for clarity

[Mpdreamz]

You can place multiple hidden entries just like you would multiple file entries.

Youm ay have hidden pages anywhere in the TOC they themselves however may not have any children.