[META] Nebari backup and restore

[pt247]

Context

This is a meta issue that tracks the progress of backup and restore.

Nebari Backup and Restore

Option 3 in RDF for backup and restore describes the overall design.

High-level architecture:

flowchart LR
    subgraph Backup and restore library
        Client
    end
    Client-->I
    subgraph Nebari
        I
    I[Backup and restore interface API]-->K[Keycloak API]
    I-->C[Conda store API]
    I-->N[User data API]
    end

Related tasks:

1. Create Nebari REST API using FastAPI to expose the existing Keycloak API.
2. Conda store API
3. User data API