Add a `switchy serve` CLI for launching services
Add a `switchy serve` CLI for launching services

Add a new sub-command `switchy serve` for launching a `switchy.Service`
process in the foreground. You can pass a list of apps to be loaded in
order using the `--app <name>` flag.

Additionally,
- change `switchy run` to `switchy dial` and support multiple apps per
  dialer
- add an apps loading helper and use it in `dial`
- tear down the originator cleanly on keyboard interrupt

sangoma/switchy