`cargo run -- init` fails with NotFound when docker is not installed.

[wjmelements]

foc-localnet(main)*$ cargo run -- init
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.21s
     Running `target/debug/foc-localnet init`
 INFO src/poison.rs:74: Poison file created at: /Users/will/.foc-localnet/state/.poison
 INFO src/commands/init/mod.rs:111: Initializing foc-localnet environment...
 INFO src/commands/init/mod.rs:32: Cleaning up previous installation...
 INFO src/commands/init/mod.rs:37: Removing /Users/will/.foc-localnet
 INFO src/commands/init/mod.rs:39: Removed previous foc-localnet installation
 INFO src/commands/init/mod.rs:45: Removing existing foc-localnet Docker images
ERROR src/main.rs:72: Command failed, poison file left in place for safety: No such file or directory (os error 2)
Error: Os { code: 2, kind: NotFound, message: "No such file or directory" }

After addressing #28 by creating the artifacts, I get another failure related to a file NotFound, though the error doesn't say which file. After investigating, I think the missing file is docker. Should prompt user to install docker in this situation.

[wjmelements]

or at least the error should be clearer that docker is the missing file

[redpanda-f]

Makes ample sense, would be added in a patch :)

[BigLep]

Can we just have a step up front that checks to make sure all the required tools are installed and then gives a useful message if any are missing?