Utility methods for new contact editor flow

- shouldShowAccountChangedNotification() to see if we need to show the dialog.

- saveDefaultAndAllAccounts() should be called when saving a newly created
contact, with the account used to save it.  This saves all writable accounts
and the default accounts to the preferences.

- getDefaultAccount() to get the default account.

- createAddWritableAccontIntent() to launch the account setup wizard.
- getCreatedAccount() to interpret the result from the wizard.

- Also implemented Parcelable for AccountWithDataSet, so now it can be
put in a Bundle.

Bug 5355671

Change-Id: Ifb86c931b43fa307b65756cf24cbef4350374c67