Support compression

[nicl]

Update: it surprises me, but actually no-one has really requested this feature in practice. I guess it's easy enough to compress things yourself. Please 👍 this issue though if you would find it helpful.

node-riffraff-artifact supports zip and tar compression. More generally, it is a useful feature for a build process.

I can see this being used in various projects, e.g.

https://github.com/guardian/dotcom-rendering/blob/main/apps-rendering/artifact.json#L8
https://github.com/guardian/dotcom-rendering/blob/main/dotcom-rendering/scripts/deploy/build-riffraff-bundle.js#L30

We should add this, probably with an extra property that would live alongside sources, called something like compression.

[Mark-McCracken]

Just looking at migrating some build pipeline from teamcity to GHA for globe-phan.
In this case, only really got 2 files to upload, but they need to be zipped, so a simple option to zip the contents of every folder could be a way.
However I've also seen some complex builds for dotcom that have about 8 folders, and some contents are zipped, some aren't, they're .deb files, so we might need a more complex way for the user to define the behaviour

[JuliaBrigitte]

Today there was a discussion about this in the DevX Channel, there definitely should be something about compression in the README. @davidfurey pointed up two different ways of zipping (directly in yml/ in package.json) in addition to running a script like this in the yml