Bundle the Java Access Bridge with NVDA. (#10515)
NVDA is a 32 bit application and requires the 32 bit Java Access Bridge client dll.
This will happily talk to 64 bit Java applications.
However, since Java 10, official 32 bit builds are no longer provided.
So that users don't have to find and install a community 32 bit build of Java themselves, bundle the JAB with NVDA.
1. Include the dll via a Git submodule.
2. Have SCons copy the dll into source/lib.
3. Modify JABHandler to load it from the versioned lib directory if appropriate. This meant reorganising initialisation somewhat, as we need NVDAHelper to get the versioned lib path, but trying to use it at module level breaks due to circular import.
4. Remove JABHandler's support for the legacy bridge, since it can no longer be used now that the proper 32 bit bridge is always present.
