add withResolvers() utility to be the analog of Promise.withResolvers()

[cowboyd]

export interface WithResolvers<T> {
  operation: Operation<T>;
  resolve(value: T): void;
  reject(error: Error): void;
}

export declare function withResolvers<T>(): WithResolvers<T>;

• implement
• API docs
• add documentation to the async Rosetta Stone