Since TWAIN is only actually available as 32-bit component on Windows,
to use it in a 64-bit program, we need a 32-bit shim program that does
all actual communication with TWAIN subsystem.

This change reimplements TWAIN implementation to be a separate 32-bit
process. Image is transfered from the shim to main program using file
mapping API.

This reverts most of commit 585d9806.
64-bit LibreOffice doesn't bundle TWAIN DSM library now. TWAIN DSM
source code is still used for TWAIN headers.

Change-Id: I46f178ad36acd97a9eff156624b99036fcbb83f8
Reviewed-on: https://gerrit.libreoffice.org/65688
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>