nfp:user: Implement IUser (#714)

* nfp:user: Implement IUser

- Based on RE of sysmod FW 1.0 and 3.0 with help of https://github.com/switchbrew/libnx/ and https://reswitched.github.io/SwIPC/ifaces.html#nn::nfp::detail::IUser
- Accurate implementation of Initialize, AttachActivateEvent, AttachDeactivateEvent, GetState, GetDeviceState, GetNpadId and GetDeviceState.
- Implementation of Finalize and ListDevices (close #638).

* reorder private var

* fix nits

Ryujinx.HLE/HOS/Services/Nfc/Nfp/State.cs

@@ -0,0 +1,8 @@
+namespace Ryujinx.HLE.HOS.Services.Nfc.Nfp
+{
+    enum State
+    {
+        NonInitialized = 0,
+        Initialized = 1
+    }
+}