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

includes/ResourceLoaderULSJsonMessageModule.php

@@ -0,0 +1,63 @@
+<?php
+/**
+ * ResourceLoaderModule subclass for loading the json
+ * based localization to client-side code.
+ *
+ * @file
+ * @ingroup Extensions
+ * @author Santhosh Thottingal
+ */
+
+/**
+ * Packages a remote schema as a JavaScript ResourceLoader module.
+ * @since 2013.11
+ */
+class ResourceLoaderULSJsonMessageModule extends ResourceLoaderModule {
+	/**
+	 * Part of the ResourceLoader module interface.
+	 * Declares the core ext.uls.i18n module as a dependency.
+	 * @return string[] Module names.
+	 */
+	function getDependencies() {
+		return array( 'ext.uls.i18n' );
+	}
+
+	/**
+	 * Gets the last modified timestamp of this module.
+	 * The last modified timestamp controls caching.
+	 * @param ResourceLoaderContext $context
+	 * @return int Unix timestamp.
+	 */
+	function getModifiedTime( ResourceLoaderContext $context ) {
+		$code = $context->getLanguage();
+		if ( !Language::isValidCode( $code ) ) {
+			$code = 'en';
+		}
+
+		$mtimes = array_map(
+			'filemtime',
+			JsonMessageLoader::getFilenames( $code )
+		);
+		// Make sure we have at least one entry
+		$mtimes[] = 1;
+
+		return max( $mtimes );
+	}
+
+	/**
+	 * Get the message strings for the current UI language. Uses
+	 * mw.uls.loadLocalization to register them on the frontend.
+	 * @param ResourceLoaderContext $context
+	 * @return string JavaScript code.
+	 */
+	function getScript( ResourceLoaderContext $context ) {
+		$code = $context->getLanguage();
+		if ( !Language::isValidCode( $code ) ) {
+			$code = 'en';
+		}
+
+		$params = array( $code, JsonMessageLoader::getMessages( $code ) );
+
+		return Xml::encodeJsCall( 'mw.uls.loadLocalization', $params );
+	}
+}