Use CALL_ORIGIN flag

CALL_ORIGIN flag allows Phone app know where the phone call
request comes from.

TESTED:
incoming calls
-> go back to calllog

outgoing calls
- make a phone call from dialpad -> go back to dialpad
- make a phone call from favorite -> go back to favorite
- make a phone call from calllog -> go to calllog
- make a phone call from call detail -> go to calllog
- make a phone call from People UI -> go to calllog
- make a phone call from dialpad and launch Phone UI
  again during the phone call -> go to calllog
- make a phone call from contact card (reached via
  phone favorite) -> go to calllog
- make a phone call from favorite and add another
  person to the phone call via in-call ui
  -> go back to "favorite" (undetermined behavior actually)
- make a phone call from dialpad or favorite, bail out the
  in-call UI. Have the recipient hang up the call.
  Then have an incoming call again. Hang up the second phone
  call.
  -> go to calllog

Must be after I4d5f825f7d5109c6ff8c27b6e53a31ca9e6b832f

Bug: 5360106
Change-Id: I7b88b245e82e96e150937ee53029d397a28a9b2d