Move shortcut processing logic into separate components.

As part of the ongoing architectural change, move shortcut processing
logic from ChooserListAdapter and ChooserActivity into spaparte
components with no functional changes; add unit tests.
The new ShrtcutToChooserTargetConverter class now contains previous
ChooserActivity’s convertToChooserTarget method; two related test cases
were moved from UnboundedChooserActivityTest class into the new
component’s test class.
The new ShortcutSelectionLogic class now contains previous
ChooserListAdapter’s addServiceResults and insertServiceTarget methods;
new unit tests added.

Test: atest IntentResolverUnitTests:ShortcutSelectionLogicTest
Test: atest IntentResolverUnitTests:ShortcutToChooserTargetConverterTest
Test: manual test
Fix: 249166394

Change-Id: I49baf7d4a435b1f270554fdf6e004875117a01d8
11 files changed