[Feature request] Support sixel graphics

[barracuda156]

@ArthurSonzogni Hi, will this be possible?

Context: I was making a fzf replacement in C++, and bumped into issue that chafa can only use block graphics with FTXUI, anything else gets turned into junk text characters. Apparently this is a limitation of FTXUI, not supporting sixel.

[ArthurSonzogni]

I have some fallback for Windows. I also request color support.

But this is too broad. I would like to request the terminal used before starting the application and apply chirurgical tweaks to support them all perfectly.

This is on the roadmap, but we are not there yet.

[barracuda156]

Currently it works on terminals without true color support, but fails on terminals with proper support for inline images, apparently because chafa detects that and tries to use what FTXUI cannot handle (that can be worked around via chafa args, but it will be better to have images when those are supported by a given terminal and fall back to block graphics otherwise).