Add a way to filter chats #79

Describe your feature:

There are a couple ways to go about this. I'm not sure if there's enough info in Delta Chat messages to know if something is a bot or not (that's fully enforced at least), but if so, automatically filtering into categories like "DMs," "Groups," "Bots," etc. would be fine.

If not, then I'd like something like Signal for Android's chat folders, where you basically add chats into manually created "folders" that you can select at the top of the chat list. Long-term, having the ability to automatically add certain types of chats into the folders would be nice (like all group chats go in one, or all chats with certain contacts go in one, etc.).

Why do you think it is useful:

The current chat list is basically a random mix of 1:1 chats, groups, and bots. It's chaotic. Most other messengers I've tried provide at least some way to filter things to make them more manageable. My current solution is to just pin everything that isn't a bot, but that's not ideal.