Add some debounce and an onwheel hack to product add to basket field

Debounce ensures we don't get a million requests if the up/down buttons are clicked rapidly. The onwheel hack adds some protection against scrolling triggering the quantity up/down. See: https://stackoverflow.com/a/51076231

app/assets/javascripts/templates/partials/shop_variant_no_group_buy.html.haml

@@ -6,6 +6,8 @@
   min: 0,
   placeholder: "0",
   "ofn-disable-scroll" => true,
+  "ng-debounce" => "500",
+  onwheel: "this.blur()",
   "ng-model" => "variant.line_item.quantity",
   "ofn-on-hand" => "{{variant.on_demand && 9999 || variant.on_hand }}",
   "ng-disabled" => "!variant.on_demand && variant.on_hand == 0",

app/assets/javascripts/templates/partials/shop_variant_with_group_buy.html.haml

@@ -9,6 +9,8 @@
       "ng-model" => "variant.line_item.quantity",
       placeholder: "{{::'shop_variant_quantity_min' | t}}",
       "ofn-disable-scroll" => true,
+      "ng-debounce" => "500",
+      onwheel: "this.blur()",
       "ofn-on-hand" => "{{variant.on_demand && 9999 || variant.on_hand }}",
       name: "variants[{{::variant.id}}]", id: "variants_{{::variant.id}}"}
     %span.bulk-input
@@ -19,6 +21,8 @@
       "ng-model" => "variant.line_item.max_quantity",
       placeholder: "{{::'shop_variant_quantity_max' | t}}",
       "ofn-disable-scroll" => true,
+      "ng-debounce" => "500",
+      onwheel: "this.blur()",
       min: "{{variant.line_item.quantity}}",
       name: "variant_attributes[{{::variant.id}}][max_quantity]",
       id: "variants_{{::variant.id}}_max"}