Use `original_filename` to match local photos

[JWCook]

The iNat API now returns the original filename for uploaded photos and sounds. This could be used to attempt to match local and remote photos.

Limitations:

• original_filename is only returned for your own photos for authenticated API calls
• Can't match filenames that changed after uploading
• May not be able to match duplicate filenames across multiple directories (if recursively scanning subdirs)
  • But other metadata like timestamps may be able to identify one unambiguous match
• Doesn't capture non-iNat local photos of the same organism. I.e., iNat observation photos are a subset of my local photos.
  • Might be possible to provide suggestions for other photos belonging to the same observation based on timestamps?

Prerequisites: user authentication is the biggest hurdle, which will require quite a bit of effort to make it both convenient for the user and reasonably secure:

• User authentication #501
• Authorization Code + PKCE flow pyinaturalist#692