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.

Adds enhanced security settings for the markdown preview. The new flow disable all scripts within the preview itself. Users can enable scripts on a per workspace basis.

When a markdown document that uses scripts is loaded, a warning is shown inside the document itself. This warning triggers a new security selector quick pick which allows users to enable or disable enahanced security in the workspace.

* upgrade telemetry used by TS ext

* upgrade telemetry used by markdown ext

* markdown-it-named-header custom slugify for non-latin characters

* Delete comment

This reverts commit 38fbba35.

Fixes #20070

**Bug**
Markdown scroll sync and other sync features do not work for untitled files. The root cause seems to be that the `main.js` markdown file is never loaded

**Fix**
Instead of a using a path without a scheme for `main.js`, use a `file://` path

**Bug**
Scroll sync not working for some users on windows

**Fix**
Root cause seems to be that windows drive/path cases can sometimes differ between preview and editor document. Adds a equality check based on `fsPath` as well

**Bug**
For long/not-terminated frontmatter in a markdown file, we can currently hang the process while trying match it using a regular expression

**Fix**
Use a more efficent regexp to do this.

* Remove unneeded d.ts files from extensions

Moves most extensions to use the lib files for the standard library that typescript provides.

* Remove a few more node.d.ts references

Adds support for editor links with fragements for markdown. This jumps to the correct header location if one can be found

* Support In Document links inside of the markdown editor

Fixes #17288

* Cleaning up code to reduce duplication

Splits the markdown scroll sync settings to be more granular.

Adds an initial implementation of scroll synrconization from the markdown preview to the editor. When the preview is scrolled, automatically scrolls the editor to reveal the same location.

This required adding a new supported reveal type `AtTop` in our API. This is already supported and used internally, but not really exposed in the public apis (except for the `revealLine` command).