Tracking issue for missing functionality in the nix command.

• nix-collect-garbage / nix-store --gc -> nix store gc
• nix-store --delete -> nix store delete
• nix-env --rollback -> nix profile rollback
• nix-env --switch-generation -> nix profile rollback --to
• nix-env --delete-generations -> nix profile wipe-history
• nix-env --list-generations -> nix profile history
• nix-store --serve
• nix-daemon -> nix daemon
• nix-store --repair-path -> nix store repair
• nix-store --dump-db - maybe not needed (nix path-info --json --all might be enough)
• nix-store --load-db / nix-store --register-validity
• nix-store --generate-binary-cache-key -> nix key
• nix-prefetch-url -> nix store prefetch-file / nix flake prefetch
• nix-prefetch-url -A -> nix build (need a flag to handle the hash mismatch)
• nix-store -q --referrers
• nix-env -qa -s flag, -c flag