`watcher` support

[tristancamejo]

When using TypeScript, you will need to run tsc --watch in a separate terminal window to compile your code. Disploy will automatically restart when you make changes to your compiled code.

https://disploy.dev/docs/getting-started/cli-framework/learning-the-workflow/dev-mode

This should now refer using the “watcher” key (2f2440d) in the Disploy config.