Dear ImGui Implementation (#598)

* added imgui as dependency

* imgui renderer/basic input implementation

* imgui: add layers system

Add video info layer to show fps. Press F10 to toggle it.

* imgui: add custom imgui config

* imgui: gamepad capture, stopping propagation

* imgui: changed config & log file path to use portable dir

* videoout: render blank frame when video output is closed

required to render imgui even when game has no video output

- fixed merge compile-error

src/imgui/imgui_config.h

@@ -0,0 +1,29 @@
+// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+// WARNING: All includes from this file must be relative to allow Dear_ImGui project to compile
+//          without having this project include paths.
+
+#include <cstdint>
+
+extern void assert_fail_debug_msg(const char* msg);
+
+#define ImDrawIdx std::uint32_t
+
+#define IM_STRINGIZE(x) IM_STRINGIZE2(x)
+#define IM_STRINGIZE2(x) #x
+#define IM_ASSERT(_EXPR)                                                                           \
+    ([&]() {                                                                                       \
+        if (!(_EXPR)) [[unlikely]] {                                                               \
+            assert_fail_debug_msg(#_EXPR " at " __FILE__ ":" IM_STRINGIZE(__LINE__));              \
+        }                                                                                          \
+    }())
+
+#define IMGUI_USE_WCHAR32
+#define IMGUI_ENABLE_STB_TRUETYPE
+#define IMGUI_DEFINE_MATH_OPERATORS
+
+#define IM_VEC2_CLASS_EXTRA                                                                        \
+    constexpr ImVec2(float _v) : x(_v), y(_v) {}