Allow persisting selection mode after the last item is deselected

[JonatanPlesko]

In cases where the app exposes a button to enter the multi-selection mode, it might be undesirable for the selection mode to be automatically turned off after the last item is deselected. Consider the following scenario:
The app exposes a "Multi-select" button that enters the selection mode and, in selection mode, exposes a "Cancel" button that exits it.

1. The user enters selection mode by pressing the multi-select button.
2. The user selects an item but then quickly deselects it as they want to select a different one.

Desired behavior -> selection mode is still active, and the user can select another item.
Current behavior -> selection mode gets deactivated after the item is deselected, and the user needs to activate it again.

The automated exiting of the selection mode after the last item is deselected might be exposed as a flag so that it can also be turned off when the long-press gesture activates the selection mode. However, that case might be more contentious from the UX perspective.