Refactoring HOS folder structure (#771)

* Refactoring HOS folder structure

Refactoring HOS folder structure:

- Added some subfolders when needed (Following structure decided in private).
- Added some `Types` folders when needed.
- Little cleanup here and there.
- Add services placeholders for every HOS services (close #766 and #753).

* Remove Types namespaces

Ryujinx.HLE/HOS/Services/Spl/IGeneralInterface.cs

@@ -0,0 +1,13 @@
+namespace Ryujinx.HLE.HOS.Services.Sm
+{
+    [Service("spl:")]
+    [Service("spl:es")]
+    [Service("spl:fs")]
+    [Service("spl:manu")]
+    [Service("spl:mig")]
+    [Service("spl:ssl")] 
+    class IGeneralInterface : IpcService
+    {
+        public IGeneralInterface(ServiceCtx context) { }
+    }
+}