Make launch of minimized task in pausing desk |returningToApp|

When entering Overview from a desk that has minimized windows, the
minimized windows won't be considered |pausing| because they were
already paused/invisible when the recents transition started. These may
still be children of a pausing desktop though, so if one of them is
launched (when exploded view shows them in the desktop tile) it should
be considered a |returningToApp| case because launching it also
relaunches the desk it belongs to, so we're returning to desk.

This avoids incorrectly marking this edge case as
|returningToApp=false|, which would lead to deactivating the desk that
this minimized app is restoring.

Flag: com.android.window.flags.enable_multiple_desktops_backend
Fix: 421471594
Test: open a desk with 5 apps (so 1 minimizes), or minimize one
manually, enter overview and click the minimized app (with exploded
view) - verify the desk and the clicked app are restored / in front

Change-Id: Ie779394a4981ef3081c4765bb2eeff324e5c212c