include `snowflake-client` and `tor` in win and macOS installers

• investigate the current state (brief testing indicates its non-functional atm)
• use the snowflake client library from tor (https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake)
• update makefile installer recipe to download and include tor and snowflake-client in macOS and windows installers
• update snowflake code to use packaged tor and snowflake-client
• Test on all three platforms by blocking the ip/hostname of the provider locally using /etc/hosts or firewall rules