We've historically shipped 32-bit Windows installers for RBTools, which

include a 32-bit Python. With RBTools 2.0, we're shipping a 64-bit

installer, but it's possible there are users who still need 32-bit.
The previous change for the installer set up some of the Wix rules to

allow for 32-bit and 64-bit builds. This completes that work by updating

our build-installer.bat to pull down both architectures for Python and

then to build two installers: RBTools-2.0-32bit.exe and

RBTools-2.0-64bit.exe.
This mostly involved performing some of the same work multiple times in

a batch file. There's also a couple fixes for issues hit when trying to

run the build process, and the removal of a probably unnecessary

condition check in the installer that prevents 32-bit installers from

being run on 64-bit (which work in practice and shouldn't be blocked).

Built the installers. Tested both on Windows, ensuring they installed

correctly, contained the expected files, and that RBTools could be run.