Add RBAC authentication support

[PierreBesson]

The testnet-manager should support authentication with roles eg. "read-only", validator-manager", "parachain-manager", which let you access a subset of the REST endpoints.

Some good fastapi security related docs to help with this task:

• https://fastapi.tiangolo.com/tutorial/security/
• https://fastapi.tiangolo.com/advanced/security/oauth2-scopes/

[aardbol]

read-only role permissions

• list nodes
  • show node info
• list validators
  • show validator info
• list parachains
  • show collator info
  • show runtime info
• show runtime info (relay chain)
  • view runtime config
• show node args
• show node labels
• show validator keys

validator-manager role permissions

• all from read-only role
• rotate session keys
• deregister validator

parachain-manager role permissions

• all from read-only role
• deregister collator
• on-/offboard parachains
• upgrade runtime

super-admin role permissions

• all from validator-manager role
• all from parachain-manager role
• upgrade relay chain runtime
• update relay chain runtime config