ResourceLoader Module for serving json based localization messages

ApiULSLocalization is still present since we have to provide live
language preview feature.

Moved the loading of json file to includes/JsonMessageLoader.php

Also moved all RL modules to includes folder.

Bug: 56509
Change-Id: Ic39dec1c484982fb07edd167e83794c0b5f470ee
Merge "ResourceLoader Module for serving json based localization messages"