[feature request] only show favorite communities

Long term I could see this become more like multireddits. We could tag a group of communities, and then filter by tag.

For example, you could have a garden tag that covers communities for composting, zeroscaping, mycology, trees, vegetables, CSAs, farming, recipes etc.

To add to that, it would be great to have multi-communities. I may want to just view my tech communities, or I may want to just view my favourites overall.