Improve wiki sidebar

What does this MR do and why?

This MR for issue #259711 (closed) Combine wiki pages with the same name as directories in trees.

When a directory and page have same name, they will combine in one node.

For example, there are a.md a/b.md a/b/c.md a/b/c/d.md

Before change UI show

After change UI show

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