Small fixes and debug mode

[jeroen1602]

Keep the old device list when resuming the app.

This stops the devices from leaving when you open and close the notification panel

Stop using runtimeType since they are compiled away (at least for web builds)

Created log page for debugging

Added debug option for release builds

lighthouse provider: Providers can now be added before back ends

Tapping the version number in settings 10 times enables debug mode.

Enabling debug mode enables:

• Adding a fake back end
• Looking at the logs
• Looking at the material test page

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 10.25641% with 35 lines in your changes are missing coverage. Please review.

Project coverage is 60.84%. Comparing base (a04bd91) to head (af8859d).

Files	Patch %	Lines
lib/data/dao/settings_dao.dart	0.00%	33 Missing :warning:
lib/widgets/content_container_widget.dart	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #256 +/- ## ========================================== - Coverage 62.53% 60.84% -1.69% ========================================== Files 35 35 Lines 1225 1259 +34 ========================================== Hits 766 766 - Misses 459 493 +34 ```

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