Add alternate intents and refinement callbacks to ChooserActivity

Allow a calling app to supply an array of additional Intents to the
system ChooserActivity.

The chooser will present a merged list of targets that can handle any
of the Intents supplied, including both the standard EXTRA_INTENT as
well as any of the intents supplied in EXTRA_ALTERNATE_INTENTS. These are
treated as ordered; EXTRA_INTENT is considered the first/primary
Intent and EXTRA_ALTERNATE_INTENTS are sorted most important first.

Targets are queried for all supplied Intents. If the same component is
returned for more than one Intent, the target is associated with the
most important Intent that matched.

This allows calling apps to supply several different payloads for an
action depending on what the intended targets are able to support. For
example, an app performing ACTION_SEND may supply image/jpeg data to
compatible targets or a hosted web link to targets that only support
text/plain. The user will have the opportunity to pick from a single
merged list of choices using the best available payload, and will not
be bothered with the implementation details of how the payload will be
delivered to the recipient.

If the calling app wishes to provide further disambiguation or
refinement after the user makes a choice, for example to let the user
choose which of the source intents to send from the primary or
alternates, show a progress dialog as a full-resolution version of a
photo is downloaded from the server before being sent along or while
reticulating splines, the caller can supply an IntentSender to
ACTION_CHOOSER including the extra EXTRA_REFINEMENT_INTENT_SENDER.
This should be the IntentSender obtained from a PendingIntent pointing
at an activity to launch to perform the refinement.

The refinement activity should report that it is finished by obtaining
the ResultReceiver from EXTRA_RESULT_RECEIVER. Available intents to
send to the selected target will be contained in EXTRA_INTENT and
EXTRA_ALTERNATE_INTENTS.

To complete the refinement and send the result along to the chosen
target, the refinement activity should select one of the supplied
intents and send it to the ResultReceiver in a Bundle with the key
EXTRA_INTENT and the result code RESULT_OK. To cancel the refinement,
and let the user select another choice, send RESULT_CANCEL.

While refinement activities cannot modify the filterEquals-affecting
fields of the Intent they return, they may modify extras to provide
additional or altered details to the final recipient. These extras
will be filled into the Intent sent to the final target.

Change-Id: I7ad4739eadd1a0e307675847ccf47ea948918a3a