Improvements to input and input configuration in the GUI. (#849)

* Improvements to input and input configuration in the GUI

* Requested changes

* nits

* more nits

Ryujinx.Common/Configuration/Hid/PlayerIndex.cs

@@ -0,0 +1,18 @@
+namespace Ryujinx.Common.Configuration.Hid
+{
+    // This enum was duplicated from Ryujinx.HLE.HOS.Services.Hid.PlayerIndex and should be kept identical
+    public enum PlayerIndex : int
+    {
+        Player1  = 0,
+        Player2  = 1,
+        Player3  = 2,
+        Player4  = 3,
+        Player5  = 4,
+        Player6  = 5,
+        Player7  = 6,
+        Player8  = 7,
+        Handheld = 8,
+        Unknown  = 9,
+        Auto     = 10 // Shouldn't be used directly
+    }
+}