Re-expose InteropObservable and InteropSubscribable (#4712)

* Expose InteropObservable and InteropSubscribable

* Changeset

* make `MachineImplementationsSimplified` hidden

* Update packages/core/src/types.ts

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

* Update packages/core/src/types.ts

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

* Update .changeset/slow-swans-punch.md

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

* Update packages/core/src/types.ts

---------

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

Author: davidkpiano

.changeset/slow-swans-punch.md

@@ -0,0 +1,5 @@
+---
+'xstate': patch
+---
+
+Ensure that `InteropObservable` and `InteropSubscribable` are present in the type definition file.

packages/core/src/types.ts

@@ -1046,7 +1046,7 @@ export type DelayConfig<
 
 // TODO: possibly refactor this somehow, use even a simpler type, and maybe even make `machine.options` private or something
 /**
- * @internal
+ * @hidden
  */
 export interface MachineImplementationsSimplified<
   TContext extends MachineContext,
@@ -1879,16 +1879,10 @@ export interface Subscription {
   unsubscribe(): void;
 }
 
-/**
- * @internal
- */
 export interface InteropObservable<T> {
   [Symbol.observable]: () => InteropSubscribable<T>;
 }
 
-/**
- * @internal
- */
 export interface InteropSubscribable<T> {
   subscribe(observer: Observer<T>): Subscription;
 }