Items/Market/Quests/misc fixes (#8987)

* use countBadge instead of class

* generic purchase action from buyModal to handle all kind of purchases - able to purchase backgrounds - return backgrounds as flat array

* List MysteryItem & Hourglass in Inventory/Items

* add Subscribers Gem Item (purchase by gold)

* fix mysterybox

* sort unlocked gear first

* add orb of rebirth to market

* remove old quest scroll + class of the quest items

* more padding on countBadge

* use the generic purchase on quests

website/common/script/content/appearance/backgrounds.js

@@ -584,12 +584,20 @@ let backgrounds = {
 };
 /* eslint-enable quote-props */
 
+let flat = {};
+
 forOwn(backgrounds, function prefillBackgroundSet (backgroundsInSet, set) {
   forOwn(backgroundsInSet, function prefillBackground (background, bgKey) {
     background.key = bgKey;
     background.set = set;
     background.price = 7;
+
+    flat[bgKey] = background;
   });
 });
 
-module.exports = backgrounds;
+module.exports = {
+  tree: backgrounds,
+  flat,
+};
+