Having _processManager.createProcess called before _createXterm was causing
some event listeners like onProcessReady to fire before they were registered
within _createXterm.

Fixes #100637

* Add CoreCommandService

For #90110

This change introduce a new service (`ICoreCommandService`) that lets high levels parts of the editor (such as webviews) hook into core commands such as undo and redo that are fired from the editor menus.

## Why is this needed?
To implement undo/redo in custom editors / webviews, we currently register special commands (`editor.action.customEditor.undo` and `editor.action.customEditor.redo`). This is not ideal since it means that users have to update multiple commands if they wish to rebind undo/redo

These custom command also are not invoked when the user goes to the `edit` menu and select `undo` or `redo`. Instead, the edit menu always calls the core `UndoCommand`

We cannot make `UndoCommand` know about custom editors because it lives in `base`

## What this change does?
This change adds a new `ICoreCommandService` that lets higher level parts of the editor override core commands such as undo and redo. We use a similar approach in the `IOpenerService`.

Right now only `undo` and `redo` are overridable. If this approach looks ok, we could also extend it to `copy`, `paste`, `cut`, and `select all`

* Add docs and clean up types

* Rework implementation

Switch from using a command service to having each command state if is overrideable or not.

This hooks up overrides for:

- Undo/redo
- cut/copy/paste

for webviews, custom editors, and notebooks

* Add ProxyCommand so that multiple registered commands can share a single implementation

* Fix compilation & missing file being referenced

* Introduce and adopt MultiCommand for Undo

* Adopt MultiCommand for Redo and SelectAll

* Adopt MultiCommand for Cut, Copy and Paste
Co-authored-by: NAlex Dima <alexdima@microsoft.com>

For #100442

When we moved the webview resource protocol to the main process, I updated the uri normalization logic so that it could load remote resources properly. This however broke VSO since their resources are still loaded from the renderer process.

This change restores the old normalization for the renderer side resource loader.

For #100442

Also make sure we use the correct scheme for the making requests

For #100442

The csp field is a string, not the csp element itself

Also adds proper typings for it

open overwrite should re-use existing editor even when the editor is optional, https://github.com/microsoft/vscode/issues/99496

fixes #86414

#100475

#99736

editors - call setEditorVisible before removing editor from DOM and thus remove onWillHide() method (fix #100271)

This should not silently fail as doing so could cause the webview to not init properly