Add Billing Admin organizational role

[BSick7]

Overview

A Billing Admin is a new organization role that will be used by organizations where the person managing the Nullstone subscription has no coding contributions or interactions. They should be allowed to do the following:

• Create new organization
• Manage subscription (create, update, cancel)
• Invite/Remove team members
• Create/Manage providers and cost providers

They should NOT be allowed to:

• create/manage stacks
• create/manage blocks
• create/manage envs
• view cost summary
• run infra updates
• deploy apps

Areas of impact

• UI to manage roles at organization level
• API Gateway to add "allows" to users with this org role for the above allowed actions
• Backend to handle new role (CRUD + jwt token creation)