* Rework how markdown server works with documents
This rewrites how the markdown server works with documents. The goal is to better handle switching between in-memory versions of a doc (from `TextDocument`) and versions of the same doc on disk. From the markdown service's POV, there is only one type of document
As part of this, I've also adopted the newest markdown language service version
* Bump package-lock versions
This brings support for code actions and source actions, along with some bug fixes
Also fixes `getAllMarkdownDocuments` to prefer open documents instead of those on disk
Fix markdown link diagnostics not updated when directories are renamed/deleted
Turns our that `createFileSystemWatcher` will not fire if a parent dir is renamed / deleted. See #60813
To fix this, I believe we have to create watchers for all parent directories too (or watch everything in the entire workspace)
* Move MD diagnostics to language server
This switches us to using the LSP pull diagnostic model with a new version of the language service
* Bump package version
* Delete unused file
