Part of #74250

- Extend `Disposable` in classes where it makes sense
- Use `DisposableStore` for lists of disposables
- Make `combinedDisposable` take arguments instead of an array (so that you can't pass in an array and then modify the array after the fact)

* adding overlayService

* addressing feedback from UX meeting

* relocating to progressService2

* remove overlayService and update progressService

* partially functioning grid view

* lots of toggling behavior and editor restore

* dimension changes

* restore layout and fix titlebar

* fix view dimensions on toggle/move

* increase timeout for debug config

* undo unnecessary changes to CSS

* put grid layout behind setting

* fix strict null checks

* address code comments from @bpasero

* changing key name

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

**Problem**
In progress service, the `ProgressState` object is quite difficult to understand. Only a subset of fields are active at a given time so the state is really more like a state machine.

When enabling strict null checks, the existing pattern is also a pain because it is not clear which subset of fields go to gether and will not be undefined

**Fix**
I've been experimenting with writing states much explicitly. This has two main points:

- Encapsulating all state in a single state object (which the progress service already does)
- Encoding each valid state very explicitly in a state machine like manner

For progress service, the encoding breaks the `ProgressState` object up into five different states that the progress service transitions between.

These values are really supposed to be undefined

* Converted another ~70 test files to strictNullChecks

These are the remaining test files that didn't require any changes to non-test file types. I'll send those in separately.

Most changes were automatic and small (`!`s).
The only non-trival change is that `extHostSearch.ts` needs an interface for its test data.

Again used [TypeStat](https://github.com/JoshuaKGoldberg/TypeStat) when possible per #65581. I'm happy to split this up into smaller PRs if you'd prefer!

* Added missing `!`s to `commands.test.ts`

Many `Promise.resolve(null)` should actually be `Promise.resolve(void 0)`. In other cases, we were missing a null return annotation.

* remove more TPromise (for #53526)

* fix failing webview integration tests on macOS

* do not instantiate TPromise (fix #62716)

* more TPromise removal and fixes

* 💄

* 💄

fixes #59471