feat: add universities and restaurants (#4)

Features:
- Allow to search for individual resources by their name
- Add new resources and their handler: Universities, Restaurants
- Added new parameter to reverse output order

Reviewed-on: #4
Co-authored-by: bdoerfchen <git@bissendorf.co>
Co-committed-by: bdoerfchen <git@bissendorf.co>

util/slices.go

@@ -31,3 +31,18 @@ func Map[T any, Tkey comparable, Tval any](s []T, transformFn func(i *T) (Tkey,
 
 	return
 }
+
+func Group[T any, Tkey comparable, Tval any](s []T, groupFn func(i *T) (groupKey Tkey, value Tval)) (out map[Tkey][]Tval) {
+	out = make(map[Tkey][]Tval)
+	for _, i := range s {
+		key, value := groupFn(&i)
+		list, exists := out[key]
+		if !exists {
+			list = make([]Tval, 0, 2)
+		}
+
+		out[key] = append(list, value)
+	}
+
+	return
+}