[WIP] Support embedded images

[andyscott]

This is still very WIP.

The idea is to intercept image escape codes (see https://buildkite.com/docs/builds/images-in-log-output) in stdout and then allow references to them later in the docs. When a reference is encountered, base64 or file url images will be copied over to the output directory.

I'm posting this now-- before it's ready-- just to get early feedback.

[tpolecat]

People have asked for something like this in the past … is the image embedding escape a standard thing, or did BuildKite invent it?

[andyscott]

It's nonstandard but seems to be getting traction. ]1337 was claimed/used by iterm2 for embedding base64'd images and buildkite has extended that with ]1338 for url images.

Buildkite currently supports both 1337 and 1338 and I was hoping to support both here.

[tpolecat]

Sounds great 👍

[andyscott]

Just a heads up that I don't think I'll have time to work on this until next week. That being said... I intend to finish it so I can use it for documenting a few projects!