Proof of concept local network file sharing

[drien]

• If clipboard contains binary data, look up the mimetype's associated extension and write the file to a tmp directory
• Start a background python http.server process in the tmp directory
• Render the computer's local network hostname+http server port to the QR code menu popup

Todo:

• Rewrite filenames from pasted_file.* if a txt is present with the originally copied filename.
  • If originally copied filename is present, only write files with matching extension?
• Add settings panel to enable file passing
  • Add warning when enabling setting about not using it on untrusted wifi as there is no encryption
• Get hostname programmatically
• Gracefully handle subprocess failing to start
• Clean up tmp directory on menu close