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