align return types for callbacks, for declare_functions

[milyin]

Some functions returns Promise, some not. I don't see any system in this.
E.g.:

interface LivelinessSubscriberOptions {
    callback?: (sample: Sample) => Promise<void>;
}
export declare class Liveliness {
     declare_subscriber(key_expr: IntoKeyExpr, options?: LivelinessSubscriberOptions): Subscriber;

but

export interface QueryableOptions {
    callback?: (query: Query) => void;
}
export declare class Session {
    declare_subscriber(key_expr: IntoKeyExpr, handler?: ((sample: Sample) => Promise<void>) | Handler): Promise<Subscriber>;

Also why for liveliness' Subscriber callback is in options, but for session's one - in parameter and there is no options (dummy at this moment)

Need to go through ts API and align it. The zenoh-c and zenoh-cpp APIs can be used as a reference

[Charles-Schleich]

@milyin regarding the declare_subscriber in session, I was trying to replicate how zenoh Rust allowed either A handler or a callback.
In Zenoh Rust the user can call declare_subscriber
and either follow with a .callback() or a .with() which allows a handler.
I can put this in a options object if needed, but it is the only option that declare_subscriber takes, so i wasn't sure if it made sense to wrap it in an object seeing as it was the only one.

I also debated having something like an object containing

{
callback:...
handler:...
}

but the possibility of a user putting both in both a callback and a handler that they can poll seemed confusing from a usage perspective.

With regards to the Async and Promise, i agree it does need to be better aligned and cleaned up.
I've been using the Rust API as a reference, but a number of additional options in the builder pattern for the declare_x functions only exist on AdvancedPubSub which I believe was not planned originally for the Typescript API.

[milyin]

The zenoh-c API takes callbacks as a parameter of function. I think we should follow this approach. I.e. lets keep declare_subscriber as is, but e.g. move callback parameter to declare_queryable parameters from QueryableOptions like it's done in zenoh-c
Adding empty SubscriberOptions are not necessary for now. In zenoh-c it's empty dummy structure. But we need to be sure that it can be easiliy added in the future.