Move ssh and deployment configuration to per-grid config module.

morph/grid/local/grid.nix

morph/grid/production/grid.nix

morph/grid/testing/grid.nix

morph/lib/customize-issuer.nix

morph/lib/customize-monitoring.nix

morph/lib/customize-storage.nix

morph/lib/issuer.nix

morph/lib/monitoring.nix

morph/lib/storage.nix

nixos/modules/issuer.nix

nixos/modules/private-storage.nix

nixos/modules/tests/private-storage.nix