New editor flow (for master)

- Added dialog-themed activity that pops up on new contact creation
in 3 cases with a variation of message when there are:
  * 0 writable accounts on the device
  * 1 writable account
  * 2+ writable accounts

- The dialog is displayed whenever a new account is added
to the device or the default account has been removed

- Once an account selection has been made by the user,
we store it in SharedPreferences using ContactEditorUtils

- Slight restyling of the account list adapter

Bug: 5355671

Original CL: Ib3343a5aea972b366a9df41b9419ad9561c2243d

Change-Id: I46f4c5687a5b6eaa68b55a568f0d737ad80dfc5c