feat: unix socket for the interactive console

Allow connecting interactive console over a unix socket picodata run --console-sock. Use picodata connect --unix to connect.

Close #354 (closed)

Ensure that

• New code is covered by tests
• API is documented
• Changelog is up to date
• (if Lua API changed) Lua API version is bumped in luamod.rs
• (if API docs changed) A follow-up doc issue is created: docs#88 (closed)