Write more stress/simulation tests

[simerplaha]

This task is at API level only. Understanding core internals is not required.

To test stability currently there are two apps that stress test SwayDB's API.

• Weather data simulation - randomly and concurrently generates weather data, concurrently overwrites generated data, concurrently streams at randomly points to assert state.
• User simulation - Random users (tested with 10 to 100 users) that concurrently perform CRUD on products at random times invoking all SwayDB APIs.

More similar stress tests are required that simulate real applications to test SwayDB's stability and production readiness.