Feature model postgresql (#842)

* Support postgresql generate

* Update template Var

* Support to generate postgresql model

* Support to generate postgresql model

* Update template

Co-authored-by: anqiansong <anqiansong@xiaoheiban.cn>

tools/goctl/model/sql/builderx/builder_test.go

@@ -118,3 +118,8 @@ func TestBuildSqlLike(t *testing.T) {
 	assert.Equal(t, sql, actualSQL)
 	assert.Equal(t, args, actualArgs)
 }
+
+func TestJoin(t *testing.T) {
+	ret := PostgreSqlJoin([]string{"name", "age"})
+	assert.Equal(t, "name = $1, age = $2", ret)
+}