CLI & Rust API crate organization

[b5]

@dignifiedquire @faassen & I have come to consensus on how to organize crates at the top level of the Iroh project:

• iroh will be the CLI crate.
• iroh-api will contain the rust API to iroh.
• iroh will import iroh-api, clap, and that's about it. All types needed to interact with iroh must be exported by iroh-api

This should clear up confusion that's arisen on a few issues:

• iroh-ctl and iroh-one #192
• iroh --version #182
• Move iroh-ctl code into the iroh-one crate #171
• Iroh ctl into iroh one iroh#296
• Build the iroh client in the Iroh API, not CLI #154
• CLI & Rust API crate organization #153
• CLI improvements: more in API, iroh-api rename, iroh get basics iroh#316

Let's mark this as closed once the rough crate organization matches this decision.

[faassen]

I'll note that this PR already goes in the direction of making iroh-ctl only depend on the API:

n0-computer/iroh#316

While I'm writing I realize I can also depend on Api for cid and a few other things, will update the PR.

The PR does the rename of iroh to iroh-api too, though not yet iroh-ctl to iroh, as that creates an absolutely unreadable PR.

[faassen]

With n0-computer/iroh#321 this is now done