Currently extensions like TS have a dev dependency on the `"vscode"` package. This pulls in a copy of `vscode.d.ts` that we end up using instead of our local `vscode.d.ts`.
This change uses the `paths` `tsconig` option so that we use our local `vscode.d.ts` instead of the one from `node_modules`
Setup a baseline tsconfig for extensions to extend. This will help make sure thatof our built-in extensions are using the recommended settings for target and so on. it also reduces duplicated code and will make updating tsconfig settings easier