Extracts team-related sections from Account Overview page into My Team page

[rhonsby]

Description

As the title states, this commit extracts all of the team-related sections from the "Account Overview" page and adds them into a new "My Team" page. All behavior remains the same.

Issue

https://github.com/papercups-io/papercups/issues/806

Screenshots

When the user is an admin

https://user-images.githubusercontent.com/1361509/117069728-d7f6a880-acfa-11eb-8feb-61c246895ab3.mp4

When the user isn't an admin

Account Overview page

Checklist

• [ ] Everything passes when running mix test
• [ ] Ran mix format
• [x] No frontend compilation warnings