Some major platform-dependent file operations refactoring.
All methods like "open file", "open file with", "show in folder"
were moved to core/file_utilities module with platform-dependent
backends. All methods interacting with DesktopServices made async.
Now each platform-dependent module declares its interface in
platform/platform_module.h file and after that includes platform-
specific headers like platform/win/module_win.h with implementation.
Also removed the legacy WinRT platform-dependent implementations.
Added LocalStorageBox for watching info and clearing local storage.
Local passcode and cloud password state display and editing done.
Temporary download location clearing link added.
Crash fixed in local storage clear + app close, now waiting for the
clearing thread to quit. Some design improvements and testing.
Left: auto update, privacy and security, local storage box +
some minor things, like design fixes, codes like loadlang and
clearing of the local storage (box) and temp download folder.
