Wraps an Observable in a Proxy that enables property chaining.
When accessing a property ending with $, it uses switchMap to chain
to that property's observable value.
When accessing a non-observable property, it returns an Observable of that property's value.
Wraps an Observable in a Proxy that enables property chaining. When accessing a property ending with
$, it uses switchMap to chain to that property's observable value. When accessing a non-observable property, it returns an Observable of that property's value.