Release 2.0 old tracking issue

[grahamc]

• move this list to a Project https://github.com/NixOS/nixops/projects/4
• Get mypy types exposed for plugin developers
• Update AWS plugin for py3 Migrate nixops-aws to python3 nixops-aws#37
• Update vbox plugin for py3 Poetry2nixify nix-community/nixops-vbox#3
• Update hetzner plugin for py3 Introduce poetry(2nix), GitHub Actions, blackify all the files nixops-hetzner#9
• Solidify the plugin dev / build experience Use Poetry & Poetry2nix for environment and plugin management #1256
• state backends Example NixOps State Backends #1264
• explore terraform integration @adisbladis looked at this and thinks it can/should be a plugin (https://github.com/adisbladis/nixops-terraform).
• explore vault integration for environment variable secrets Vault Integration for Secrets #1289
• identify old features to delete
• perform real life integration tests with real servers and real providers on every PR, including using external plugins Deploy as part of CI #1290
• allow specifying the version of Nixpkgs from within the network.nix expression Specify NIX_PATH / nixpkgs from within a network's expression itself #1291

features to delete or move to plugins:

• encryptedLinksTo support
• autocrypt?
• backups?
• storeKeysOnMachine