Makefile for setup

[FintanH]

There are setup steps that are "documented" in the Dockerfile, but it would make sense to have a Makefile to make it easy for someone to come along, spin up the rustup, cargo, etc. stuff. Then it's as easy as running ci/run to check if everything works for them.

[cloudhead]

If the only purpose is to run a script, may I suggest just having a script?

[FintanH]

Well, the purpose is to ensure that people have anything that's needed to call ci/run such as having cargo-deny and whatever else is needed. How this is done, I don't really mind. Makefile can be seen more as a suggestion :)