Add SGR-Pixels (mouse mode 1016)

[salt-die]

Description of the new feature

Now that sixel is implemented, SGR-Pixels mouse mode would be a nice feature to have. Also helps to implement features such as, e.g., smooth scrolling.

I've searched through issues and only found two references to this feature (below), so hopefully this isn't a duplicate:

#448 (comment) with response from @j4james :

I wasn't considering 1016, but I do have a POC of the DEC locator mode. There's no point in doing either of them until we have sixel, though, because the pixel coordinates will need to be tightly coupled to the sixel resolution.

And listed as not supported here #10531 (comment) from @DHowett

Would prefer 1016 over DEC Locator since it seems to be more widely used?
dankamongmen/notcurses#2326
wezterm/wezterm#1457
https://github.com/mahmoudimus/jexer/blob/16d27b6f4182e3c2cfecd7673934ebe09782861a/README.md?plain=1#L26C1-L26C70
Aetf/libtsm#29
xtermjs/xterm.js#4092

Proposed technical implementation details

No response

[j4james]

Also helps to implement features such as, e.g., smooth scrolling.

That's neat, but it's disappointing that they felt the need to resort to proprietary sequences. Here's a similar demo running in OpenConsole using DEC sequences from the 1980's. They could have achieved this 30+ years ago if terminal devs weren't constantly reinventing the wheel.

This is using my POC of DEC Locator mode btw. I never got around to turning it into a PR, because it required significant rewrites to the mouse handling, and I suspect there are things that got broken in the process. Implementing mode 1016 will almost certainly have the same problem.

But I'm not opposed to mode 1016. I just prefer the DEC Locator mode because it's more powerful, and has been around for 30 more years.