Create food and recipe classes with tests

Create classes for ingredients, recipes and register. Functionality may still be expanded upon. Not all classes have complete unit tests or JavaDoc yet.

src/main/java/no/ntnu/idatt1002/demo/data/recipes/FoodItem.java

+package no.ntnu.idatt1002.demo.data.recipes;
+
+public enum FoodItem {
+
+    ONION("onion"),
+    MINCED_MEAT("minced meat"),
+    POTATO("potatoes"),
+    YELLOW_CHEESE("yellow cheese"),
+    WHEAT_FLOUR("wheat flour"),
+    MILK("milk"),
+    TOMATO("tomato"),
+    ORANGE("orange"),
+    LEMON("lemon"),
+    SALSA_SAUCE("salsa sauce")
+    ;
+
+    public final String label;
+
+    FoodItem(String label) {
+        this.label = label;
+    }
+}