<r4-admin>

[oskarrough]

New component <r4-admin.

• It takes two attributes: supabaseUrl and supabaseServiceRoleKey.
• If both are defined, it'll create a new Supabase admin client and start rendering.

For now, it lists all users and any channels they are associated with. Each user has a delete button which will wipe their channel(s) and auth.user.

Closes https://github.com/radio4000/supabase/issues/17