This ensures we clean these up on dispose

This reverts commit b4aa5aee.

This switches our notebooks to always use contributed markdown rendering instead of our built-in markdown renderer

We'd held off on switching over due to accessibility. I've tried to address this using the `aria-describedby` attributed to link the markdown container with a copy of rendered (and sanitized) html from the webview.

Also make sure we register it

This reverts commit 7c01395d.

This reverts commit 7a976501, reversing
changes made to 22576768.

- Add them for statics
- Add them in a few notebook cases

After editing a cell, we were incorrectly rendering a cell twice. This is caused by `this.textModel` becoming undefined in `MarkdownCellViewModel`

Don't remove the textmodel when closing the notebook editor, and cleanup how the textmodel ref is created
Fix #117936 more

Change cell TextModel handling, fix #117936

Forgot in previous commit

* display change is less noticeable than top. re #118021.

* remove markdown preview only when it is hidden or deleted.

* wrong change.

* Update terminalProcessManager.ts

* Fix #117903

* inset -> output.

* logging.

* markdown cell minHeight leads to wrong init height calculation.

* fix padding

* add a bit more logging

* allow cache

* Try to avoid extra promise chaining for posting into a webview

This moves the `<webview>` based webviews to use a queue of pending messages while the webview itself is being prepared. This lets us avoid calling `.then` if the webview has already been resolved

* clean up for merge.

* no optimization for scrollTop > 0

* Use visibility instead of display to show markdown cells

* Use hideMarkdownPreview when a cell is folded

* viewport trick.

* warmup viewport +/- 1 on scroll.

* 💄

* guard npe.

* warmup based on view height.

* Update terminalProcessManager.ts

* Use fixed heights for markdown headers

* Fix createMarkdownPreview creating webview markdown cells even if they are disabled

* Remove test file
Co-authored-by: NDaniel Imms <daimms@microsoft.com>
Co-authored-by: NRachel Macfarlane <ramacfar@microsoft.com>
Co-authored-by: NMatt Bierner <matb@microsoft.com>

Fixes #118581

Make sure we don't update a markdown cell's height based on the preview if only the editor is visible