Allow moving wiki pages from the UI

What does this MR do?

Allow moving wiki through the wiki structure using the input fields.

Why was this MR needed?

Right now, the only thing we could do is to rename wiki pages. If we set the page title to 'foo/bar' instead of moving the page to that path it will move or rename the page to the current_tree/foo/bar.

We have added a little behavior to the title input in the wiki page edit form. If the page is inside a subtree of folders and you want to move it to the root one, you have to add '/' to the beginning of the title (there is also a tooltip in the form explaining that).

Screenshots

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes #37273 (closed)