Feature Request: Unicode placeholders

[AbeEstrada]

It would be beneficial if the Kitty Unicode Placeholder could be an optional feature. This would be helpful for applications that combine text and images for rendering (reader), work with tmux, or, in my case, less.

The central idea is that we use a single Private Use Unicode character as a placeholder to indicate to the terminal that an image is supposed to be displayed at that cell. Since this character is just normal text, Unicode aware application will move it around as needed when they redraw their screens, thereby automatically moving the displayed image as well, even though they know nothing about the graphics protocol.

[AbeEstrada]

For reference func write_unicode_placeholder