IPC services refactoring (#726)

* IPC services refactoring

- Use custom Attributes to handle services.
- Add a way to set the permissions and fix the bsd service to use it.
- Little cleanup.
- C#7.1 is required.

* fix var name

* fix syntax

* Change Permission to Parameter

* Delete BsdServicePermissionLevel.cs

* Fix Linq

Ryujinx.HLE/HOS/Services/Aud/IAudioRendererManager.cs

@@ -9,6 +9,7 @@ using static Ryujinx.HLE.HOS.ErrorCode;
 
 namespace Ryujinx.HLE.HOS.Services.Aud
 {
+    [Service("audren:u")]
     class IAudioRendererManager : IpcService
     {
         private const int Rev0Magic = ('R' << 0)  |
@@ -24,7 +25,7 @@ namespace Ryujinx.HLE.HOS.Services.Aud
 
         public override IReadOnlyDictionary<int, ServiceProcessRequest> Commands => _commands;
 
-        public IAudioRendererManager()
+        public IAudioRendererManager(ServiceCtx context)
         {
             _commands = new Dictionary<int, ServiceProcessRequest>
             {