Pinentry support

## Feature Description

There's polkit support now, but there's still no support for [pinentry](https://wiki.archlinux.org/title/GnuPG#pinentry).

## Use Case

From https://www.gnupg.org/related_software/pinentry/index.html:

> *pinentry* is a small collection of dialog programs that allow GnuPG to read passphrases and PIN numbers in a secure manner. There are versions for the common GTK and Qt toolkits as well as for the text terminal (Curses).

## Compositor

Is this feature specific to one compositor?

- [x] All compositors
- [ ] niri
- [ ] Hyprland
- [ ] dwl (MangoWC)
- [ ] sway

## Proposed Solution

Add support for pinentry. Perhaps the codebase for polkit can be reused?

## Alternatives/Existing Solutions

Right now I'm still using `pinentry-gnome3` as an alternative.