Feat: add minimalist utilities in the container image

[cr1cr1]

Rationale: the existing container image is too barebones to be used in production scenarios.

If you need to do some additional scripting for example for some backup routine (like cleanup, retention, basic filtering either locally or remotely), you have to either add apk packages at runtime or build another container image with the current one as base.

For example, since s5cmd supports json output, one could use jq to get and then script to manipulate programmatically the remote s3 objects

The resulting uncopressed image is 31.5MB as compared to current 25.7MB:

[igungor]

Hey @cr1cr1, Docker image is intentionally minimal because it's meant to distribute s5cmd only. You may create your own image with jq and s5cmd in it if you'd like.