Fix serious text/background misalignment in Controls dialog under many user-defined Windows font DPI settings

The background picture is now being stretched according to the size of the client area of the dialog.

In addition, change the encoding of ppsspp.rc to UCS-2/UTF-16 LE as it seems to be the only way to fix displaying of a certain non-ASCII character 'å' used in the version info of the compiled executable under cp1252-incompatible Windows locales.