Default tab feature for 4.3.0+

Description

Default tab feature has been removed in 4.3.0 (6ab3e4b4).

Similar to quick exit, this now causes issue considering there are multiple navigation destinations available.

In any case, the destinations are just one click away and people who liked updates fragment as default tab can also rest easy since we have updates notifications implemented that let's us open the tab by default.

The feature is still needed because:

1. Not all users want automatic update check/notifications.
2. Opening the apps page introduces unnecessary network usage (fair amount of apps icons etc.), which may not be desired on mobile networks with limited traffic.