Move ContactLoader related code to ContactsCommon

This CL simply moves classes from Contacts into ContactsCommon.

This is needed so that Dialer can use ContactLoader related code
for b/11294679. A ContactLoader will also be needed in the future
to allow InCallUI to download hi-res photos while in call.

Bug: 11294679
Change-Id: If56a60aed2003ac7b8fcedac7ce4f1a7503bce94
43 files changed