feat: add "Edit this page" link

[AriPerkkio]

Adds support for "Edit this page" link.

---
type: part
title: Basics
editPageLink: https://github.com/stackblitz/tutorialkit/tree/main/packages/template/src/content/tutorial/:path
---

Inherited editPageLink can be disabled on lower hierarcy:

---
type: lesson
title: Some lesson
editPageLink: false
---

See bottom-left corner:

[bolt-new-by-stackblitz]

Run & review this pull request in StackBlitz Codeflow.

[Nemikolh]

This is looking great! 😃

One immediate feedback that comes to mind is regarding the use of :path. I think I see where this is coming from but I would prefer if we used ${path} because:

• It's not behaving as route parameters in express-like servers where :path would only match a segment (so only until the next /). Here it instead does a string replace.
• To use the same convention everywhere. If we're sold on using ${variable} for string interpolation in the metadata then let's use it everywhere we need that feature.

Note that I'm also open to a different syntax. I picked ${variable} initially because it's similar to JavaScript's template literal syntax.

[AriPerkkio]

One immediate feedback that comes to mind is regarding the use of :path. I think I see where this is coming from but I would prefer if we used ${path} because:

I've changed the pattern to ${path} now - it's better to be consistent with rest of the codebase. And partTemplate was already following this pattern. The :path convention was from VitePress.

[Nemikolh]

Nice!! Really good work on this 🤩

Love it ❤️