Fix SMS quick reply behavior for MultiSim devices.

Quick Reply will default to SIM slot 0 for MSIM devices, even if it is
not an active SIM. This will cause a loop of fail that tries to send the
message over and over.

- Abstract the Msim prompt dialog into it's own class to be shared
  between QuickMessagePopup and ComposeMessageActivity.
- Actually use the default *active* sim slot here, or prompt the user
  if SMS prompt is enabled.

Change-Id: Ieedd4e8dd5e35caaade34ee78d30d676648370b7