Trigger a "config changed" event on changes to .garden/local-config.yaml

[eysi09]

This is e.g. necessary for when users run a link command while Garden is running in watch mode in another process. Currently, the user would need to restart the watch process after running the link command for Garden to pick up the changes.

Notes on implementation

The link command updates the ./garden/local-config.yaml so we'd need watch that file for changes and trigger the `projectCnofig event.

The ./garden directory is excluded from the watcher so we need to handle the local-config.yaml file specifically.

Finally, we need to make sure the changes get picked up by the watcher instance. The instance is global and does not change even though a new instance of the Garden class is created, so we'd need to update it with the new paths (or reset it).

[eysi09]

Alternatively we could also just have the link/unlink commands trigger the change and bypass having to watch the local-config.yaml file.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.