Bug 1035279 - [Messages][Refactoring] Move error codes mapping from dialog.js to a separate file. r=julien

* ErrorDialog moved to a separate file;
* Removed ErrorDialog dependency on Errors mapping;
* Errors mapping moved to a separate file;
* ErrorCodes organized into enums.
instead of using constants like this, how about namespacing the string themselves? This one would be `ThreadUI.NonActiveSimCardToSendError`, the ones from MessageManager would be prefixed by `MessageManager.`.