bpo-36590: Add Bluetooth RFCOMM and support for Windows. (GH-12767)

bpo-36590: Add Bluetooth RFCOMM and support for Windows. (GH-12767)

Support for RFCOMM, L2CAP, HCI, SCO is based on the BTPROTO_* macros
being defined. Winsock only supports RFCOMM, even though it has a
BTHPROTO_L2CAP macro. L2CAP support would build on windows, but not
necessarily work.

This also adds some basic unittests for constants (all of which existed
prior to this commit, just not on windows) and creating sockets.

pair: Nate Duarte <slacknate@gmail.com>