feat: add plist.py for decrypting the .plist files to FindMyAccessory

[NickCrews]

No description provided.

[NickCrews]

@malmeloo OK I incorporated all the changes you suggested, thanks for such a quick review!

I also added a --log-level flag to the CLI, and in a followup commit adjust the API so that the output dir is optional, and the output is always printed in JSON, so that you can chain it better, eg with python -m findmy decrypt | jq '.[] | select(.name == "my airtag")' > my_airtag.json

Take a look and confirm this change is OK.

Also could consider renaming to python -m findmy list_paired or list_accessories or something more inline with the python function name??? I realize now that maybe we want to make it clear this isn't scanning bluetooth for accessories.

[malmeloo]

Nice, thanks! I think the CLI naming is OK for now, I might rename it in the future but we'll see about that later. Having a CLI at all is already a huge plus!

I will try to test it myself soon and merge if all looks ok.

[malmeloo]

Finally found some time to test it out. Thanks for your contribution!