Add support for Nautilus 43

As said on the mailing list:

Just wanted to let you know that due to Nautilus API changes in the upcoming 43 release scheduled for September 21, I had to change nautilus-python’s API as well. It looks like you will be mainly affected by the removal of LocationWidgetProvider, which probably needs to be replaced by a string of GTK dialogues. Hopefully, the migration guide will help you. Feel free to e-mail me or ask on Nautilus’s Matrix chat if you have any questions.

• GNOME Schedule: https://wiki.gnome.org/FortyThree
• GtkDialog docs: https://docs.gtk.org/gtk4/class.Dialog.html
• Migration guide: https://gnome.pages.gitlab.gnome.org/nautilus-python/nautilus-python-migrating-to-4.html
• Nautilus’s chat: https://matrix.to/#/#nautilus:gnome.org