Suggest Event add-ons

Here's a small MR to add suggestions for the event add-ons that already exist in the contrib space, instead of reproducing them as small, additional recipes within Drupal CMS.

One small nit from me, no objection otherwise.

However, the bigger question here lands squarely in @pameeela's bailiwick. If we do decide to ship these add-ons with Drupal CMS, then we'll want to add test coverage to prove that they all apply cleanly on top of both the Events recipe and the Starter recipe.

IMHO if the recipes won't be applied as part of the initial site install, it makes more sense to not load dependencies until the recipes are going to be applied. Happy to defer to @pameeela on this, however.

Hmm. I'm not sure this is sufficient because we will be showing the event recipe in the onboarding, but are unlikely to include the idea of 'optional additions' at that point, because we want to keep the decisions to a minimum and get folks into their sites. So I definitely think there is value in having them presented in the recipes UI. (This UI is currently being scoped out and we do hope to have it for v1!)

If someone doesn't apply the event recipe in the onboarding, then we could use the suggestions to show optional add-ons during the later application.

Okay, there are two options here:

1. Keep the three recipes in contrib, and bring them into the project template as dependencies.
2. Merge them wholesale into Drupal CMS, and deprecate the contrib projects.

Either way, we can show them in Project Browser. I like door #2. @tim.plunkett is agnostic. It sounds like Pam is more on the door #2 side.

I think @mandclu must choose.

I'm good with the second option.

Okay, great. So the next steps here:

• Add these recipes as dependencies to project_template/composer.json
• Add a little test coverage to the starter recipe which confirms that they all apply on top of it

Now that the decision has been made, this can land during beta.