Rewrite Save Data & Impl Save Data Dialog (#824)

* core: Rewrite PSF parser & add encoder

add .sfo hex pattern to /scripts

* core/fs: allow to mount path as read-only

* common: Add CString wrapper to handle native null-terminated strings

* SaveData: rewrite to implement full functionality

* mock value for SYSTEM_VER

* SavaData: backup features

* SavaData: SaveDataMemory features

* imgui Ref-counted textures

- has a background thread to decode textures

* imgui: rework gamepad navigation

* PSF: fixed psf not using enum class for PSFEntryFmt (was a standard old ugly enum)

- Add null check to CString when itself is used in a nullable field

* SaveDataDialog implementation

- Fix Mounting/Unmounting check of SaveInstance

src/imgui/imgui_texture.h

@@ -0,0 +1,45 @@
+// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <filesystem>
+#include <imgui.h>
+
+namespace ImGui {
+
+namespace Core::TextureManager {
+struct Inner;
+} // namespace Core::TextureManager
+
+class RefCountedTexture {
+    Core::TextureManager::Inner* inner;
+
+    explicit RefCountedTexture(Core::TextureManager::Inner* inner);
+
+public:
+    struct Image {
+        ImTextureID im_id;
+        u32 width;
+        u32 height;
+    };
+
+    static RefCountedTexture DecodePngTexture(std::vector<u8> data);
+
+    static RefCountedTexture DecodePngFile(std::filesystem::path path);
+
+    RefCountedTexture();
+
+    RefCountedTexture(const RefCountedTexture& other);
+    RefCountedTexture(RefCountedTexture&& other) noexcept;
+    RefCountedTexture& operator=(const RefCountedTexture& other);
+    RefCountedTexture& operator=(RefCountedTexture&& other) noexcept;
+
+    virtual ~RefCountedTexture();
+
+    [[nodiscard]] Image GetTexture() const;
+
+    explicit(false) operator bool() const;
+};
+
+}; // namespace ImGui