IMP: use same `SQLite session` for both logger and dashboard

[Keegan-Evans]

Currently mqtt-data-logger' and sensor-dashboard each create and use their own SQLite session, which leads to both processes encountering OperationalError: database lockedfairly regularly,sensor-dashboardis somewhat robust to this(3 backed off retries), butmqtt-data-logger` is not and will simply crash and restart(see this issue).

Possible Solutions:

• PREFERRED bring both sets of code into this repository, and have the main function create a single session object that is used to run both apps relevant issue

• figure out a way to share context/have one or the other share their session object with the other process.