Changed domains, configured links between VisaApplication and Applicant,created generic repository and repositories for domains

SchengenVisaApi/Domains/LocationDomain/City.cs

@@ -0,0 +1,15 @@
+namespace Domains.LocationDomain
+{
+    /// Model of a city
+    public class City : IEntity
+    {
+        /// Unique identifier of the <see cref="City"/>
+        public Guid Id { get; private set; } = Guid.NewGuid();
+
+        /// Name of the city
+        public string Name { get; set; } = null!;
+
+        /// <see cref="LocationDomain.Country"/> in which the city is located
+        public Country Country { get; set; } = null!;
+    }
+}