Color input fields using FZF scheme colors

### Checklist

- [x] I have read through the manual page (`man fzf`)
- [x] I have searched through the existing issues
- [ ] For bug reports, I have checked if the bug is reproducible in the latest version of fzf

### Output of `fzf --version`

0.60.3

### OS

- [x] Linux
- [ ] macOS
- [ ] Windows
- [ ] Etc.

### Shell

- [ ] bash
- [x] zsh
- [ ] fish

### Problem / Steps to reproduce

I'm curious if it's possible to color the FZF prompt of some external command using pre-defined FZF colors. Here's what I mean.

Let's say I have a file with some lines split by spaces. When filtering with FZF I would like the first item to be colored using the `list-bg` color:


We already have `--nth` and `--with-nth` to control search based on fields. It would be interesting to allow users to apply color schema 'tags' to certain fields and color the FZF prompt accordingly. Maybe something like:

```bash
# Color the first field text using list-bg and color the second field using hl
--nth-color '1:list-bg,2:hl'
```

Obviously, this isn't super critical. It's like half feature request and half question if it's possible to achieve something like this by other means. Thank you in advance.

## Alternatives considered

When using a custom color scheme I can use `--ansi` to manually set the color of the first item to the matching color. That's what I'm already doing with a custom history widget.


However, this approach breaks down when users use their own color scheme.