Add Option to Enable/Disable Screen Capture (#1418)

Veracrypt currently appears in screenshots and screen captures,
which can unintentionally expose sensitive information, such as
the fact that Veracrypt is running or the location of your volumes.

Both Windows and macOS offer mechanisms to exclude specific windows
from being captured. While not foolproof, this is a useful preventative
measure. The method is a no-op for Linux/FreeBSD.

For more details on the wxWidgets API, see:
https://docs.wxwidgets.org/3.2/classwx_top_level_window.html#a337b9cec62b0cbd3b1b1545a83270f64

src/Main/CommandLineInterface.h

@@ -84,6 +84,7 @@ namespace VeraCrypt
 		VolumeInfoList ArgVolumes;
 		VolumeType::Enum ArgVolumeType;
         shared_ptr<SecureBuffer> ArgTokenPin;
+        bool ArgAllowScreencapture;
         bool ArgDisableFileSizeCheck;
         bool ArgUseLegacyPassword;
 #if defined(TC_LINUX ) || defined (TC_FREEBSD)