feat(terminal)!: the rest of the kitty graphics protocol, sixel and iterm2 images

[clearloop]

Lands in 0.1.26. Refs #41.

• Kitty graphics: placements by id (a=p, p, I) and every delete target, z layers, source rectangles and cell offsets, zlib payloads, Unicode placeholders, relative placements, and animation (a=f, a=a, a=c, d=f)
• File, temp file and shared memory transfers behind Emulator::set_local_media; a=q answers what the transmission would
• CSI 14 t / CSI 16 t answered, replies in stream order
• Sixel images, with the DA1 sixel claim behind Emulator::set_advertise_sixel
• iTerm2 inline images, multipart files and animated GIFs
• Breaking: terminal::scanner holds Scanner, Segment and Iterm; the graphics types are #[non_exhaustive]; PlacedImage and Placement gained fields; lower-case d=a/d=i keep image data; default z paints over text