ui: Add Open Cemu folder & delete shader cache buttons (#524)

* Add option to open UserDataPath folder
* Add option to remove shader caches

Co-authored-by: ssimco <ssimco-github@proton.me>

src/gui/MainWindow.h

@@ -86,6 +86,7 @@ public:
 	void OnMouseWheel(wxMouseEvent& event);
 	void OnClose(wxCloseEvent& event);
 	void OnFileMenu(wxCommandEvent& event);
+	void OnOpenCemuFolder(wxCommandEvent& event);
 	void OnLaunchFromFile(wxLaunchGameEvent& event);
 	void OnInstallUpdate(wxCommandEvent& event);
 	void OnFileExit(wxCommandEvent& event);