refactor: avoid usage of callbacks and use timeout for hathor-core client

[luislhl]

Acceptance Criteria

• We should avoid passing callbacks between functions if the same thing can be achieved without them
• We should use a default timeout and allow changing it when calling the methods of the HathorCoreAsyncClient

Security Checklist

• [ ] Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.