Most services are implemented as command/queries

Code cleanup

ModernKeePass.Application/Security/Commands/GenerateKeyFile/GenerateKeyFileCommand.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Threading.Tasks;
+using MediatR;
+using ModernKeePass.Application.Common.Interfaces;
+
+namespace ModernKeePass.Application.Security.Commands.GenerateKeyFile
+{
+    public class GenerateKeyFileCommand : IRequest
+    {
+        public string KeyFilePath { get; set; }
+        public bool AddAdditionalEntropy { get; set; }
+
+        public class GenerateKeyFileCommandHandler : IAsyncRequestHandler<GenerateKeyFileCommand>
+        {
+            private readonly IPasswordProxy _security;
+            private readonly IFileProxy _file;
+
+            public GenerateKeyFileCommandHandler(IPasswordProxy security, IFileProxy file)
+            {
+                _security = security;
+                _file = file;
+            }
+
+            public async Task Handle(GenerateKeyFileCommand message)
+            {
+                byte[] entropy = null;
+                if (message.AddAdditionalEntropy)
+                {
+                    entropy = new byte[10];
+                    var random = new Random();
+                    random.NextBytes(entropy);
+                }
+                var keyFile = _security.GenerateKeyFile(entropy);
+                await _file.WriteBinaryContentsToFile(message.KeyFilePath, keyFile);
+            }
+        }
+    }
+}