fmt: fix interface fields alignment (#19866)

Author: felipensp

vlib/builtin/js/array.js.v

@@ -424,7 +424,7 @@ pub interface JS.TypedArray {
 mut:
 	byteLength JS.Number
 	byteOffset JS.Number
-	length JS.Number
+	length     JS.Number
 }
 
 pub interface JS.Uint8Array {

vlib/builtin/js/builtin.v

@@ -16,7 +16,7 @@ pub fn panic(s string) {
 pub interface IError {
 	// >> Hack to allow old style custom error implementations
 	// TODO: remove once deprecation period for `IError` methods has ended
-	msg string
+	msg  string
 	code int // <<
 	msg() string
 	code() int

vlib/builtin/result.v

@@ -7,7 +7,7 @@ module builtin
 pub interface IError {
 	// >> Hack to allow old style custom error implementations
 	// TODO: remove once deprecation period for `IError` methods has ended
-	msg string
+	msg  string
 	code int // <<
 	msg() string
 	code() int