Support symbols for image previewing

[shajra]

Please describe the problem you're trying to solve

I'm not an expert on image rendering in a terminal. What I know is from using the chafa executable, which seems to support the following formats:

• --format kitty
• --format iterm
• --format sixels
• --format symbols

Yazi does the first three well where it can. But the fallback seems to require Überzug++ to get Chafa working (I believe as a library).

The "symbols" format of Chafa is just fancy character art, but it can be surprisingly pleasant for what it is. Such an option would give people using modest terminals who are not interested in installing/configuring Überzug++ something more than nothing.

Would you be willing to contribute this feature?

• Yes, I'll give it a shot

Describe the solution you'd like

I would want to use the current fallback if Überzug++ is detected; otherwise, use simple ANSI art along the lines of what chafa --format symbols currently does.

Additional context

No response