More ACTION_CHOOSER ClipData migration.

Traverse into both EXTRA_INTENT and any EXTRA_INITIAL_INTENTS when
migrating extras to ClipData.  Also, we don't need to promote these
ClipData into the parent, since the platform ChooserActivity will
issue any required permission grants for the final user-selected
Intent.  Even if we wanted to, we can't combine the various child
Intent flags into anything meaningful at the ACTION_CHOOSER level.

Bug: 17580604
Change-Id: I6b5a1f572a7edf8135e059c67a2643d3736e40ab