Most services are implemented as command/queries

Code cleanup

ModernKeePass.Application/Settings/Commands/PutSettingCommand.cs

@@ -0,0 +1,25 @@
+using MediatR;
+using ModernKeePass.Application.Common.Interfaces;
+
+namespace ModernKeePass.Application.Settings.Commands
+{
+    public class PutSettingCommand<T> : IRequest
+    {
+        public string Key { get; set; }
+        public T value { get; set; }
+
+        public class PutSettingCommandHandler : IRequestHandler<PutSettingCommand<T>>
+        {
+            private readonly ISettingsProxy _settingsProxy;
+
+            public PutSettingCommandHandler(ISettingsProxy settingsProxy)
+            {
+                _settingsProxy = settingsProxy;
+            }
+            public void Handle(PutSettingCommand<T> message)
+            {
+                _settingsProxy.PutSetting(message.Key, message.value);
+            }
+        }
+    }
+}