Refactor ime lazy loading

* Do not load anything unless input field is focused
* Split the setup function to smaller functions
* Introduce $wgULSImeSelectors to allow configuration and avoid
  duplication of selectors in two places.

Change-Id: If5a476e66681dde9f0b72f619d35ddf6255246ac

Resources.php

@@ -45,6 +45,7 @@ $wgResourceModules['ext.uls.ime'] = array(
 	'dependencies' => array(
 		'ext.uls.init',
 		'ext.uls.preferences',
+		'jquery.ime',
 	),
 	'messages' => array(
 		'uls-ime-helppage',
@@ -110,7 +111,6 @@ $wgResourceModules['ext.uls.interface'] = array(
 		// We can not delay webfonts loading since it is required
 		// immediately after page load
 		'ext.uls.webfonts',
-		'ext.uls.ime',
 	),
 	'messages' => array(
 		'uls-plang-title-languages',