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/template/new.go

@@ -5,7 +5,7 @@ var New = `
 func New{{.upperStartCamelObject}}Model(conn sqlx.SqlConn{{if .withCache}}, c cache.CacheConf{{end}}) {{.upperStartCamelObject}}Model {
 	return &default{{.upperStartCamelObject}}Model{
 		{{if .withCache}}CachedConn: sqlc.NewConn(conn, c){{else}}conn:conn{{end}},
-		table:      "{{.table}}",
+		table:      {{.table}},
 	}
 }
 `