Support restoring a user defined backup

[olirice]

Projects that have been paused for > 90 days can not be restored on the platform automatically. Instead we allow them to download their logical backup.

This PR updates our tooling so users can attempt to restore their downloaded backup into a realistic supabase db where they'll have all the extensions they need.

This PR updates nix run .#start-client to

• name the arguments to start-client
• add a help --help
• optionally allow a custom migration file (the backup)

If a backup file is not passed, start-client runs the default supabase migrations. If a file is passed, the default migrations are skipped because they'll be included in the user's backup

There will be a followup PR in supabase/supabase documenting how to use this repo to restore a db from a backup

› nix run .#start-client
Usage: nix run .#start-client -- [options]

Options:
  -v, --version [15|16|orioledb-16]  Specify the PostgreSQL version to use (required)
  -f, --file FILE                    Provide a custom migration script
  -h, --help                         Show this help message

Description:
  Starts an interactive 'psql' session connecting to a Postgres database started with the
  'nix run .#start-server' command. If a migration file is not provided, the client
  initializes the database with the default migrations for a new Supabase project
  if a migrations file is provided, default migrations are skipped
  If no migration file is provided, it runs the default Supabase migrations.

Examples:
  nix run .#start-client
  nix run .#start-client -- --version 15
  nix run .#start-client -- --version 16 --file custom_migration.sql
  nix run .#start-client -- --version 16 --port 5433