Support starts a pair of intent/shortcut and task to split

Add startIntentAndTask and startShortcutAndTask APIs to support starts a
pair of intent/shortcut and task to split with shell-transition.

Fix: 250875492
Test: atest WMShellFlickerTests
Test: manual check start tasks or start intent/shortcut with task flow
      with shell-transition enabled
Change-Id: Ia79cf5e1990089f2a92895fd09b8f813d9381093