Android app - No notification for lack of network connection

[pcenov]

Observed behavior

Currently there's no clear indication to an android user that the network connection connection has been lost. This can cause confusion for the user.

Expected behavior

Detect lost network connection and notify the user.

Steps to reproduce the issue

1. Install this Windows build and this Android build
2. Setup the Windows app as a server.
3. Launch the android app and start adding learner accounts.
4. Turn off the device wi-fi connection.
5. Attempt to add another learner - an "Incorrect username and password" validation message is displayed instead of a notification that there is no network connection and then the last added learner is automatically signed in. (highly confusing behavior)
6. Attempt to import a channel - the option for importing from Kolibri Studio (online) is disabled while the option to import from local network or internet is not (again not clear to the user what is going on)

Additional information

Connection lost during learner import:

The Select a source modal:

Usage Details

• OS: Windows 10, Android 11
• Browser: Chrome

@jtamiace and @radinamatic

[rtibbles]

Some of this should be addressed by some of the 0.16 work, the rest we can further triage to 0.17.

[bjester]

I believe this requires some Android integration, to support the reactivity on the network changes and connectivity status. There's likely challenges in relaying that reactive information using python-for-android, so this might be better suited along side chaquopy