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/Fs/FileSystemProxy/IStorage.cs

@@ -0,0 +1,65 @@
+using LibHac;
+using Ryujinx.HLE.HOS.Ipc;
+
+namespace Ryujinx.HLE.HOS.Services.Fs.FileSystemProxy
+{
+    class IStorage : IpcService
+    {
+        private LibHac.Fs.IStorage _baseStorage;
+
+        public IStorage(LibHac.Fs.IStorage baseStorage)
+        {
+            _baseStorage = baseStorage;
+        }
+
+        [Command(0)]
+        // Read(u64 offset, u64 length) -> buffer<u8, 0x46, 0> buffer
+        public ResultCode Read(ServiceCtx context)
+        {
+            long offset = context.RequestData.ReadInt64();
+            long size   = context.RequestData.ReadInt64();
+
+            if (context.Request.ReceiveBuff.Count > 0)
+            {
+                IpcBuffDesc buffDesc = context.Request.ReceiveBuff[0];
+
+                // Use smaller length to avoid overflows.
+                if (size > buffDesc.Size)
+                {
+                    size = buffDesc.Size;
+                }
+
+                byte[] data = new byte[size];
+
+                try
+                {
+                    _baseStorage.Read(data, offset);
+                }
+                catch (HorizonResultException ex)
+                {
+                    return (ResultCode)ex.ResultValue.Value;
+                }
+
+                context.Memory.WriteBytes(buffDesc.Position, data);
+            }
+
+            return ResultCode.Success;
+        }
+
+        [Command(4)]
+        // GetSize() -> u64 size
+        public ResultCode GetSize(ServiceCtx context)
+        {
+            try
+            {
+                context.ResponseData.Write(_baseStorage.GetSize());
+            }
+            catch (HorizonResultException ex)
+            {
+                return (ResultCode)ex.ResultValue.Value;
+            }
+
+            return ResultCode.Success;
+        }
+    }
+}