Add option to align FindMyAccessories key generation

Sometimes the key generation diverges for example if the accessory has no power. FindMy solves this be re-aligning the key generation if a btle connection is established. FindMy.app stores there alignment records in the `KeyAlignmentRecord` directory.

This PR extends the FindMyAccessory class to read those records during `from_plist`-generation and re-sync the key generation by this

examples/real_airtag.py

@@ -4,6 +4,7 @@ Example showing how to fetch locations of an AirTag, or any other FindMy accesso
 
 from __future__ import annotations
 
+import argparse
 import logging
 import sys
 from pathlib import Path
@@ -19,10 +20,15 @@ ANISETTE_SERVER = "http://localhost:6969"
 logging.basicConfig(level=logging.INFO)
 
 
-def main(plist_path: str) -> int:
+def main(plist_path: Path, alignment_plist_path: Path | None) -> int:
     # Step 0: create an accessory key generator
-    with Path(plist_path).open("rb") as f:
-        airtag = FindMyAccessory.from_plist(f)
+    with plist_path.open("rb") as f:
+        f2 = alignment_plist_path.open("rb") if alignment_plist_path else None
+
+        airtag = FindMyAccessory.from_plist(f, f2)
+
+        if f2:
+            f2.close()
 
     # Step 1: log into an Apple account
     print("Logging into account")
@@ -43,10 +49,9 @@ def main(plist_path: str) -> int:
 
 
 if __name__ == "__main__":
-    if len(sys.argv) < 2:
-        print(f"Usage: {sys.argv[0]} <path to accessory plist>", file=sys.stderr)
-        print(file=sys.stderr)
-        print("The plist file should be dumped from MacOS's FindMy app.", file=sys.stderr)
-        sys.exit(1)
+    parser = argparse.ArgumentParser()
+    parser.add_argument("plist_path", type=Path)
+    parser.add_argument("--alignment_plist_path", default=None, type=Path)
+    args = parser.parse_args()
 
-    sys.exit(main(sys.argv[1]))
+    sys.exit(main(args.plist_path, args.alignment_plist_path))