Improve connection lifecycle process (Connect -> Refresh -> Reconnect/Recovery)

[DJBenson]

The app is designed to manage its connection in such a way that if the data becomes stale (the age of the data is older than the refresh threshold) then the data is refreshed. If the inverter dropped the connection in the meantime, the app should recover automatically through a tiered approach, using the same TCP tunnel, creating a new one or completely disconnecting and starting over.

This seems to work well in the main but issues reported suggest there are still improvements to be made. Some potentially related issues include;

• App stuck in "Refreshing" forever
• Stale data / no refresh within refresh window
• Missing features (as the connection dropped and a subsequent refresh invalidated the state object)

There is no single fix for this so this bug is to track improvements to address these issues.

[DJBenson]

Multiple changes have been made in build 50 which should address at least some of these.

Also a new "Polling Method" switch has been added to the settings page to allow testers to try different methods to see which works best and also whether there are any performance considerations of each method.