pgtype.OID type should only be used for scanning and encoding values

It was a mistake to use it in other contexts. This made interop
difficult between pacakges that depended on pgtype such as pgx and
packages that did not like pgconn and pgproto3. In particular this was
awkward for prepared statements.

This is preparation for removing pgx.PreparedStatement in favor of
pgconn.PreparedStatement.

extended_query_builder.go

@@ -17,7 +17,7 @@ type extendedQueryBuilder struct {
 	resetCount int
 }
 
-func (eqb *extendedQueryBuilder) AppendParam(ci *pgtype.ConnInfo, oid pgtype.OID, arg interface{}) error {
+func (eqb *extendedQueryBuilder) AppendParam(ci *pgtype.ConnInfo, oid uint32, arg interface{}) error {
 	f := chooseParameterFormatCode(ci, oid, arg)
 	eqb.paramFormats = append(eqb.paramFormats, f)
 
@@ -62,7 +62,7 @@ func (eqb *extendedQueryBuilder) Reset() {
 
 }
 
-func (eqb *extendedQueryBuilder) encodeExtendedParamValue(ci *pgtype.ConnInfo, oid pgtype.OID, arg interface{}) ([]byte, error) {
+func (eqb *extendedQueryBuilder) encodeExtendedParamValue(ci *pgtype.ConnInfo, oid uint32, arg interface{}) ([]byte, error) {
 	if arg == nil {
 		return nil, nil
 	}