Support additional SASL mechanisms on Windows

Only the ANONYMOUS and PLAIN SASL mechanisms are supported on Windows, according to https://github.com/apache/qpid-proton/blob/69f5dfe7eb22432dbec666b5c7a1dca786c93657/python/setup.py.in#L170-L184.

Apparently, Windows itself implements GSSAPI, GSS-SPNEGO, EXTERNAL and DIGEST-MD5 https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-adts/a98c1f56-8246-4212-8c4e-d92da1a9563b in a C++ system library https://stackoverflow.com/questions/43146229/example-of-c-client-digest-md5-sasl-auth-with-windows, https://docs.microsoft.com/en-us/previous-versions/ms995352(v=msdn.10)?redirectedfrom=MSDN.

Cyrus SASL can be built for Windows, according to its documentation. https://wiki.mozilla.org/LDAP_C_SDK_SASL_Windows, https://github.com/cyrusimap/cyrus-sasl/blob/a162471d0edb390f5b233b25067773df0b3b99a4/docsrc/sasl/windows.rst

The linked patch in GitHub PR enables building with Cyrus SASL.