Add unit test for HearthCommand

[chosww]

Is your feature request related to a problem?

While I was working on task to add support for Livewire in Hearth, I had to update HearthCommand file. The update caused CodeCov CI check failure, because we are not testing HearthCommand.

Describe the solution you'd like

I found a doc for testing Command: https://laravelpackage.com/06-artisan-commands.html#testing-a-command. Initial approach would be follow the documentation.

Describe alternative solutions you've considered

Excluding HearthCommand from CodeCov would be a way to remove CodeCov complaint: https://phpunit.readthedocs.io/en/9.5/configuration.html#the-exclude-element.