Move acitve/visible notebook editors to window namespace.

Fixes https://github.com/microsoft/vscode-internalbacklog/issues/1472

Fix #107933

Fixes #108170

Part of #107903

related to #103454

This reverts commit 362b7f3b.

Fixes #107969

* file model - allow to load a model with contents and use it for working copy move/copy

* remove unused code

* 💄

* more tests

Add keybinding shortcut for "Preserve case" replace option

push diff editor relayout to next tick, to avoid height change side effects when updating original editor first.