Add UnwrappedPromise and DeepPartial types

Signed-off-by: Cameron Diver <cameron@balena.io>

typings/global.d.ts

@@ -6,3 +6,9 @@ type Callback<T> = (err?: Error, res?: T) => void;
 
 type Nullable<T> = T | null | undefined;
 type Resolvable<T> = T | Promise<T>;
+
+type UnwrappedPromise = T extends PromiseLike<infer U> ? U : T;
+
+type DeepPartial<T> = T extends object
+	? { [K in keyof T]?: DeepPartial<T[K]> }
+	: T;