Make Android update screen (UpdateGate) optional

[tjanez]

Related: #1945, #2199, #2236

I use a custom Android ROM with the Aurora Store as the Google Play store alternative.

Even with ROSE Wallet now being available in production track on Google Play, I always get the following error:

Could we make a setting to manually disable this?

If we could detect whether the system uses Google Play vs. Aurora Store (or some other alternative store) and disable the check automatically, that would be even better. But that might be quite complex?

[buberdds]

1. we can extend app settings (similar to privacy screen) so user can control this
2. return UPDATE_NOT_AVAILABLE when update plugin hits UNKNOW status or just ignore it. if we can't reliably check for updates don't bother user with this screen (I don't see value in it)