Revert "Add UI to configure keyboard-to-controller mapping (#308)"

This reverts commit fdb13a3b90.

src/input/keys_constants.h

@@ -1,30 +0,0 @@
-// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-#pragma once
-
-enum KeysMapping : int {
-    Start_Key = 0,
-    Select_Key,
-    LAnalogDown_Key,
-    LAnalogLeft_Key,
-    LAnalogUp_Key,
-    LAnalogRight_Key,
-    PS_Key,
-    RAnalogDown_Key,
-    RAnalogLeft_Key,
-    RAnalogUp_Key,
-    RAnalogRight_Key,
-    DPadLeft_Key,
-    DPadRight_Key,
-    DPadUp_Key,
-    DPadDown_Key,
-    L2_Key,
-    L1_Key,
-    Cross_Key,
-    R2_Key,
-    Circle_Key,
-    R1_Key,
-    Square_Key,
-    Triangle_Key
-};