fixes #22135

Add Command for navigating around visible editors/viewlets/repl

Fixes #19078

Fixes #22409

Fixes #22494

**Bug**
References without a definition can cause the markdown table of contents provider to break

**Fix**
Pass in an empty environment to markdown-it `parse` to prevent the null dereference on invalid links.

fixes #22513

Adding check of full folder name instead of suffix

fixes #21062

fixes #21151

fixes #21251