Readonly helps with type guards and code comprehension

This allows to declare more services declaratively.

Enables strict null checking for `textEditorModel`. I also had to add a few null supressions to difficult errors.

* new reg service and always on mnemonics

* missed one

* use new node module and accessibility service

* add typings

* adopt accessibility service

* make it lazy

This state is currently unused and make no sense. Update the signature to  prevent ever trying to go into this state

More manual conversion of index based for loops to for-of loops

Code like:

```
private readonly _onDidEncounterLanguage: Emitter<LanguageId> = new Emitter<LanguageId>();
```

Does not need to repeat the `Emitter<LanguageId>` type annotation

Fixes #64633

* remove more TPromise (for #53526)

* fix failing webview integration tests on macOS

* do not instantiate TPromise (fix #62716)

* more TPromise removal and fixes

* 💄

* 💄

debt - let menu listen to (new) menu registry change events instead of listing to the extension host being ready. that simplifies this a lot and help with show menu sooner

#60565

We compile using the alwaysStrict flag so these directives are not needed

This part removes most `use strict` directives that are right after the file header