Auto-assign a default role to new members, and swipe to open channels on mobile web

This is two enhancements in one. Wouldn't it be best if separated into two enhancement tickets?

I did not make it a separate one because I felt like the 2nd one may already be fixed/it won't exist on the mobile app when it comes out. Besides didn't feel it was that important. If I need to I'll add it as a separate one