Product Group renamed to Menu Category

Extracted Product Group -> Group_type to a a new object called Sale Category.
Moved tax from product to Sale Category for uniform taxes on types of sales.

bookie/src/app/core/menu-category.ts

@@ -1,9 +1,8 @@
-export class ProductGroup {
+export class MenuCategory {
   id: string;
   name: string;
   discountLimit: number;
   isModifierCompulsory: boolean;
-  groupType: string;
   isActive: boolean;
   isFixture: boolean;
   sortOrder: number;

bookie/src/app/core/product.ts

@@ -1,13 +1,13 @@
-import {ProductGroup} from './product-group';
-import {Tax} from "./tax";
+import {MenuCategory} from './menu-category';
+import {SaleCategory} from "./sale-category";
 
 export class Product {
   id: string;
   code: number;
   name: string;
   units: string;
-  productGroup: ProductGroup;
-  tax: Tax;
+  menuCategory: MenuCategory;
+  saleCategory: SaleCategory;
   price: number;
   hasHappyHour: boolean;
   isNotAvailable: boolean;

bookie/src/app/core/sale-category.ts

@@ -0,0 +1,7 @@
+import {Tax} from "./tax";
+
+export class SaleCategory {
+  id: string;
+  name: string;
+  tax: Tax;
+}