Add tests for sql row

[snuyanzin]

A bit more crazy stuff...
SQL ROW is already supported, now more tests for that
so just with usage of compositeField it's possible to have SQL nested structure like ROW
e.g.

Schema.of(compositeField("row_row",
       new Field[]{field("name1", () -> "1"), compositeField("row", new Field[]{field("name", () -> "2")})}))

could be used to generate something like that

INSERT INTO "MyTable" ("row_row") VALUES (ROW('1', ROW('2')));