hid: Initial Keyboard Support (#684)

* hid: Initial Keyboard Support

This adds basic hid keyboard support.

Because of OpenTK.Input limitations, some specials keys aren't mapped.

* Fix code style

* Fix for loops code style

* Make hid keyboard feature toggleable

* Address comments

* Fix 2 other nits

* Apply jd's suggestion

Ryujinx/_schema.json

@@ -19,6 +19,7 @@
     "enable_fs_integrity_checks",
     "enable_aggressive_cpu_opts",
     "controller_type",
+    "enable_keyboard",
     "keyboard_controls",
     "gamepad_controls"
   ],
@@ -442,6 +443,17 @@
         "NpadRight"
       ]
     },
+    "enable_keyboard": {
+      "$id": "#/properties/enable_keyboard",
+      "type": "boolean",
+      "title": "(HID) Keyboard Enable",
+      "description": "Enable or disable direct keyboard access (HID) support (Provides games access to your keyboard as a text entry device).",
+      "default": true,
+      "examples": [
+        true,
+        false
+      ]
+    },
     "keyboard_controls": {
       "$id": "#/properties/keyboard_controls",
       "type": "object",