Add a new field for the full name to the account index that allows
exact lookups by full name. In AccountResolver do lookups by full name
via the account index, if an account index exists.
This is a preparation for moving the account properties from ReviewDb
into git.
Change-Id: I1dc2eae98280b70354b48f6333d23b89acc8501a
Signed-off-by: Edwin Kempin <ekempin@google.com>