rewrite sops backend for secret generation and add tests

pkgs/clan-cli/clan_cli/machines/facts.py

@@ -0,0 +1,9 @@
+from .folders import machine_folder
+
+
+def machine_has_fact(machine: str, fact: str) -> bool:
+    return (machine_folder(machine) / "facts" / fact).exists()
+
+
+def machine_get_fact(machine: str, fact: str) -> str:
+    return (machine_folder(machine) / "facts" / fact).read_text()