Could not create IMMV including types which don't have an equality operator

[yugo-n]

For example, box and json type cannot be used.

test4=# create table boxes (b box);
CREATE TABLE
test4=# create incremental materialized view v as select * from boxes ;
ERROR:  could not identify an equality operator for type box
test4=# create table j (d json);
CREATE TABLE
test4=# create incremental materialized view v as select * from j ;
ERROR:  could not identify an equality operator for type json

jsonb can be used.

test4=# create table j2 (d jsonb);
CREATE TABLE
test4=# create incremental materialized view v as select * from j2 ;
SELECT 0

[yugo-n]

Since #92 , we can create IMMV using such base tables, but we cannot insert/delete/update the table, which results in the same error. We should be prevent from creating IMMV at the definition time.