Consider sub-commands for the watchmaker cli

Right now, running watchmaker will immediately start executing. A safer default would be just to print the help. The current functionality could be implemented behind a sub-command, instead, e.g. watchmaker run. This would be introduced without changing the current behavior, just implementing the sub-command(s) and printing a deprecation warning when invoked without a sub-command.

Some sub-command ideas...

• init - Copy config file to /etc/watchmaker.yaml or /etc/watchmaker/config.yaml
• install - Invoke an install method from workers in the config, intended to install the config mgmt pkgs
• run - Invoke the run method from workers, intended to run the config mgmt tool
• clean - Invoke the clean method from workers, intended to remove config mgmt pkgs (not any hardening applied by the tool)
• worker - Run a specific worker from the config

Start by locating the watchmaker CLI entry point and reviewing how the current no-subcommand invocation dispatches work. Define the intended subcommands and their behavior from the issue, then verify that the existing invocation remains functional while printing help for the safer default and a deprecation warning where required.