Part of #63832

* Manually added strict null checks in around 70 files

* Fixed tsconfig.strictNullChecks.json merge fail

* Touched up a few unnecessary type changes

* Removed files already in other PRs

Code like:

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

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

- False now really means false
- The default is true for all platforms

Fixes #65037

Part of #65035

And that tasks wait for terminal process ready before checking to see if task process ended to fire

Related #58828

This reverts commit dbdbbe52.

Part of #60565

#60565

In these cases, the programmer has explicitly indicated that the type should be nullable

Using a custom version of the node typings is causing a lot of pain while trying to upgrade our build to use `@types` instead of the `d.ts` files we have to maintain. I believe we primarily maintain our own version for two reason:

- Custom require function
- setTimeout and other timer functions return NodeJs.timer instead of a number

These can both be delt with, the first by using interface augmentation and the second by switching to use any types for timer. I believe that the pain of maintaining our own node `d.ts` outweighs the benefits here

This change switches us to use the standard @types/node package for our node typings

Part of #53526

Fixes #58015

Added a try catch around pty spawn to handle case where the file passed into spawn does not exist (#58912)

Fixes #31301

This reverts commit 1f7ce421.

This reverts commit 95c0e072.

Fixes #56217

We just want to make sure it's killed, ignore the ex

Fixes #54754

The terminal process no longer exists so this isn't needed anymore