Allow adding a new board

[ ] Write an SQL query to add a new board (this is probably already in queries.sql) [boba-backend]
[ ] Create a permission to add a new board [boba-backend]
[ ] Create an endpoint to add a new board [boba-backend]
[ ] Improve the existing image upload/edit component to allow us to reuse it for board avatars [boba-components]
[ ] Add new page to realm admin panel to manage boards [boba-frontend]
[ ] Add form to board management panel to add board [boba-frontend]

BobaBoard / issues