Launch all activities into the same root task

When multiple activities are launched through a PendingIntent, all
activities need to be launched onto the same root task. To ensure
that, the launch root task information from the passed-in
SafeActivityOptions object are used to create a new
SafeActivityOptions object for bottom activities.

Bug: 243630981
Test: Drag and drop "new conversation" shortcut of Messages to split
      atest test_selectiveCloneLunchRootTask
Change-Id: I437db94f0019cf561464527147da08ccf4ac4cd3