Update contributing.md - Githubissues

Design decisions:

contributing.md is moved into the dev-docs folder, all of our development specific docs will go in there.
contributing.md now covers both linux and mac setup, as we will be using macbooks for development.
Building shotover and building integration tests are intentionally listed separately so that packagers can avoid pulling in deps only needed for testing.
linux and macOS specific setup are moved into their own documents to avoid 4th level subheadings.
linux deps are included in a runnable script to make it easy to setup a new machine for shotover development
- in the future I will change ec2-cargo and windsock-cloud-docker to use this script instead.
install_ubuntu_packages.sh name doesnt really make sense anymore but its called in lots of places so I left renaming it for a follow up PR.

Some other misc changes:

removed installation of uidmap from some installation scripts, I think it was needed for docker rootless install which we no longer use.
Moved gcc-aarch64-linux-gnu out of install_ubuntu_packages.sh and into build.yaml
- done since that script is now specifically for installing the cpp cassandra driver and the build.yaml is the only place that needs that gcc package.

Future work:

ec2-cargo is left as a TODO, ec2-cargo needs some work before it should be documented.
running windsock and criterion benchmarks.

shotover / shotover-proxy