Add separate category header string for clone accounts

This change adds the string identifiers for clone category headers and
content descriptions. Additionally, we add an xml property to set the
default clone category header that will be used as a header for cloned
accounts in the account management dashboard.

Bug: 260181765
Test: Tested by flashing on sunfish and checking account manager UI

Change-Id: Ie0a351bb48033298b8283b7351d3d4d9a102d331