Add comments in seeds

[josepjaume]

🎩 User Story

In order to test comments, it'd be valuable to have some as seeds.

In order to make it easier, I'd create a Decidim::Comments::Seed.comments_for(resource) that creates test comments for a particular resources. Then decidim-pages can add that in its seeds file, as well as meetings, proposals and potentially other resources.

📋 Related documentation

None

🎯 Acceptance criteria

There's pages with comments created when seeding the app.

📌 Related issues

None

[oriolgual]

I'd wait until @beagleknight finishes adding votes to comments so we can create the seeds with votes.

[beagleknight]

We can remove the block after merging #381

[oriolgual]

Closed by #501