Consolidate project data to one yaml file

[valencik]

This PR consolidates all the project data to one yaml files as done in #274 but without the categorization, which could perhaps come later in a separate PR.

It also makes sure cats comes first in the list of cats-... named projects.

I've kept changes to a minimum here, but I feel like this would make it easier to maintain reasonable category values across all the projects. Or ensure that all projects have particular metadata.

[jducoeur]

Mixed feelings, at first glance. Purely from a scalability POV, I kind of prefer having them separate, rather than in a single big file. But I may well be overly precious there -- in practice, it's probably fine. And if this allows us better control over the order of the listings, it may well be the right decision.

[valencik]

Just a quick note to self, if we go with this approach we'll want to update the migration template: https://github.com/typelevel/governance/blame/main/.github/ISSUE_TEMPLATE/2-project-migration.md#L22

[zmccoy]

I think the single file is fine just ease of ordering etc. We can just keep an eye on if this becomes a pain.

[samspills]

Also a fan of the single file, and yah not impossible to chunk back up into individual files if we want that in the future