Remove dependencies from the 'arti' crate

Right now the arti CLI and proxy crate uses the following dependencies:

• tor-client (This is okay, it's our public API.)
• tor-socksproto (This is okay since the arti crate)
• tor-config (This is our configuration parser.)
• tor-proto (For connection parameter types)
• tor-dirmgr (For configuration types.)
• tor-rtcompat (For building a runtime.)
• tor-circmgr (For configuration types.)

We should refactor our APIs so that the arti crate can be built to not require tor-proto, tor-dirmgr, or tor-rtcompat. This will mean giving tor-client better wrappers for these crates.