This change adds partial SOCKS5 forward proxy support to the snowflake.
If TOR_PT_PROXY is set, and the value corresponds to a SOCKS5 proxy, the snowflake will use this proxy for communication with broker and proxy.
Things To Look At:
- Forked pion/transport should be moved to another location.
- To keep a non-breaking API, some functions will have a second form.
- Additionally 3rd party library is introduced. It has insufficient documents.
- If the proxy is not ready or incompatible, a silent error occurs.
(Subtask of #40069)