Re-add WordPress plugin builds

[QWp6t]

Summary

With WordPress working toward enabling plugin dependencies, we see an opportunity to release Acorn as a plugin again so that it can be marked as a dependency by other plugins.

Additional context

We had this feature previously but it was removed.

There is also desire to enable plugin updates from the WordPress admin. I'm currently unfamiliar with this process. But @Log1x found some docs that might be helpful.

We should ensure that there is a way to filter plugin dependency checks to tell WordPress that the Acorn plugin is installed when it's loaded via Bedrock instead of WordPress.

[QWp6t]

We should ensure that there is a way to filter plugin dependency checks to tell WordPress that the Acorn plugin is installed when it's loaded via Bedrock instead of WordPress.

After some research, this isn't possible. Instead, we would need to create a command that publishes a plugin stub.