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_config.h

@@ -26,4 +26,7 @@ extern void assert_fail_debug_msg(const char* msg);
 #define IMGUI_DEFINE_MATH_OPERATORS
 
 #define IM_VEC2_CLASS_EXTRA                                                                        \
-    constexpr ImVec2(float _v) : x(_v), y(_v) {}
+    constexpr ImVec2(float _v) : x(_v), y(_v) {}
+
+#define IM_VEC4_CLASS_EXTRA                                                                        \
+    constexpr ImVec4(float _v) : x(_v), y(_v), z(_v), w(_v) {}