Added interfaces to read and write data in DB and added DbContext implementing these

SchengenVisaApi/Infrastructure/Database/IWriter.cs

@@ -0,0 +1,25 @@
+using Domains;
+
+namespace Infrastructure.Database
+{
+    /// Writes data to data storage
+    /// <remarks><see cref="IUnitOfWork"/> should be used to save changes</remarks>
+    public interface IWriter
+    {
+        /// Add <paramref name="entity"/> to data storage
+        /// <param name="entity">Entity to add</param>
+        /// <param name="cancellationToken">Cancellation Token</param>
+        /// <typeparam name="T">Entity type</typeparam>
+        Task AddAsync<T>(T entity, CancellationToken cancellationToken) where T : class, IEntity;
+
+        /// Update <paramref name="entity"/> in data storage
+        /// <param name="entity">Entity to update</param>
+        /// <typeparam name="T">Entity type</typeparam>
+        void Update<T>(T entity) where T : class, IEntity;
+
+        /// Remove <paramref name="entity"/> from data storage
+        /// <param name="entity">Entity to remove</param>
+        /// <typeparam name="T">Entity type</typeparam>
+        void Remove<T>(T entity) where T : class, IEntity;
+    }
+}