Dialer: Cleanup BaseAccountType

* Remove all messengers - they are deprecated - leaving only
  "custom" behind (like GoogleAccountType and deprecation notice also
  says to do)
* Align PhoneType and EmailType with Google as well -
  we also did that on Contacts already - see commit e0b9c83 and
  commit 573c7bc

Change-Id: I85bf768e138fdea250d3565e7592f7f803332a46