engine: Add ReplacementUtils

Add a utility class for replacing a property within a message
that represents a collection of items with their value.
The utility also supports replacements of a counter if specified
as ${PropertyName_COUNTER}.

Change-Id: Ia9d30047f090057561bd1a3e16f3edb4e724bd8d
Signed-off-by: Moti Asayag <masayag@redhat.com>