DDL Importer needs to better handle constraint naming in generated model

When importing DDL, the generated model can have errors when multiple constraints are present. For example the following DDL:

CREATE FOREIGN TABLE G1( e1 integer, e2 varchar, e3 date, PRIMARY KEY (e1, e2), INDEX(e2, e3), ACCESSPATTERN(e1), UNIQUE(e1), ACCESSPATTERN(e2, e3))

includes two access patterns which end up being named the same. The importer should auto increment the names to avoid name conflicts.