postgres: replace the package lib/pq with pgx (#15343)

* WIP replacing lib/pq

* change timezome param to be URI format

* add changelog

* add changelog for redshift

* update changelog

* add test for DSN style connection string

* more parseurl and quoteidentify to sdk; include copyright and license

* call dbutil.ParseURL instead, fix import ordering

Co-authored-by: Calvin Leung Huang <1883212+calvn@users.noreply.github.com>

builtin/logical/postgresql/backend.go

@@ -8,7 +8,6 @@ import (
 	"sync"
 
 	log "github.com/hashicorp/go-hclog"
-
 	"github.com/hashicorp/vault/sdk/framework"
 	"github.com/hashicorp/vault/sdk/logical"
 )
@@ -108,10 +107,10 @@ func (b *backend) DB(ctx context.Context, s logical.Storage) (*sql.DB, error) {
 			conn += "?timezone=utc"
 		}
 	} else {
-		conn += " timezone=utc"
+		conn += "&timezone=utc"
 	}
 
-	b.db, err = sql.Open("postgres", conn)
+	b.db, err = sql.Open("pgx", conn)
 	if err != nil {
 		return nil, err
 	}