MSIM: Refactor MMS settings to support N-SIM

Instead of repeating properties in the main preference activity for each SIM,
create a "Subscription Settings" activity that has a tab for each SIM. Per-SIM
properties are refactored to the helper class MSimPreferencesController so
that that we can reuse code between the single sim and N-SIM cases.

Change-Id: I51a9946d7c40a330749d0e01bc5a551b9b5908b4