Opens a search dialog to find and open a file.
Supports searching text within files.
Supports limiting search to just PDFs.

Dependencies: Rofi, Recoll
The assumption is that this is used as an i3 script bound to some keybind, but that's not required.
Make sure Recoll has indexed your file system, else this won't work.

See `fff.toml` for an example config file.

Inspired by https://github.com/andersju/zzzfoo