Support command builder

[konard]

Similar to:

Command.make("cat", "./some-file.txt").pipe(
  Command.stdout("inherit"),
  Command.exitCode
)

(https://effect.website/docs/platform/command and https://doc.rust-lang.org/std/process/struct.Command.html)

Make something like:

$.command("cat", "./some-file.txt").pipe(
  $.command.stdout("inherit"),
  $.command.exitCode
).run();

That will remove problems with quoting and shell injection.

So the $.command chain should produce a runnable string, and we should be able to run it immediately if we want to.