perf(chatScroll): Improve performance of the commonly used js libraries

Adding .pragma library to the js libraries because the entry point on these libraries were called multiple times. There is no need to share the qml context with these libraries.
Use find() instead of forEach() on emoji array to find an item

ui/StatusQ/src/StatusQ/Core/Utils/Emoji.qml

@@ -82,10 +82,9 @@ QtObject {
         return value.match(/<img class=\"emoji\" draggable=\"false\" alt=\"(.+?)\" src=\".+?\/StatusQ\/src\/assets\/twemoji\/.+?" width=\"[0-9]*\" height=\"[0-9]*\" style=\"(.+?)\" ?\/>/g, "$1");
     }
     function getEmojiUnicode(shortname) {
-        var _emoji;
-        EmojiJSON.emoji_json.forEach(function(emoji) {
-            if (emoji.shortname === shortname)
-                _emoji = emoji;
+
+        const _emoji = EmojiJSON.emoji_json.find(function(emoji) {
+            return (emoji.shortname === shortname)
         })
 
         if (_emoji !== undefined)

ui/StatusQ/src/StatusQ/Core/Utils/emojiList.js

@@ -1,3 +1,5 @@
+.pragma library
+
 var emojiCategories = [
     "time",
     "smileys-and-people",

ui/StatusQ/src/StatusQ/Core/Utils/xss.js

@@ -4,6 +4,7 @@
  * Most this code was copied from https://github.com/leizongmin/js-xss and slightly modifed
  * to work with JavaScript resource loading in QML.
  */
+.pragma library
 
 var defaultCSSFilter = new FilterCSS();