Implement CWin32Directory

like it was done for CPosixDirectory in PR #4838 by @mkortstiege 

* Rewritten from the scratch
* Added support for `DIR_FLAG_NO_FILE_INFO` flag
* Fixed `Create()` to return false if file (not directory!) with same name exist
* Files with `System` attribute treated as hidden
* Unified with Posix: files with name started from dot are marked as hidden
* Unified with Posix: if directory created with name started from dot, attribute `Hidden` is applied 

Now we can recommend addons creators to use directories starting from dot to store additional files (like `.clearart`) on media library and they will be hidden on all platforms.
The idea of DIR_FLAG_NO_FILE_INFO is to not do expensive stat()'s on the filesystem for size+date.  In this case, the expense is close to free (compared with listing the dir), so it seems pointless to wrap it.

Note that due to the way the flag is passed, this has consequence for main directory listing if the user sets this flag via advancedsettings.xml - this is not the intended behaviour.