Fixes #95481

Got reverted by 744b418a

Fixes #75209

Our custom menus try to restore focus when they are called. This ends up calling `.focus` on the webview dom node, which just triggers the problem 870700e9 fixed

To workaround this, override `.focus` on the node so that it always uses our implementation of focus that shells out to the real focus impl after a short delay.

Fixes #95487

This makes sure we properly handle the case where you hold down cmd and then open a new webview

#77131

For #77131

- Rename `onDidEdit` to `onDidChange`
- Allow custom editors to fire a `CustomDocumentContentChangeEvent` that only marks the editor as dirty but does not enable undo/redo. The only way for editor to get out of this dirty state is to either save or revert the file

Part of #94921

Improve sync flow from Accounts UI

- remove inactive state
- use available and unavailable states

fixes #95378

Fixes #95324

Fixes #95399

Notebook: support hidden regions

fixes #94962