build: turbo cache, generic build dockerfile, dependency caching in github actions

[PeterBaker0]

Makes various build improvements

• utilises turbo repo remote cache in build and lint pipeline
• produces an automated Dockerfile.build which is capable of building any node based target in the monorepo without specifying manually the dependencies to bundle in the output
• updates README to explain Dockerfile.build
• utilises npm i cache in the Github Actions

[luke-mcfarlane-rocketlab]

LGTM - tested locally, and reviewed actions output

[stevecassidy]

This all looks good. My only comment is tangential - I updated the node version in a few places to 20.9.0 for an earlier PR but note that you're just specifying node 20 in a few places here. That sounds like a better idea so should we use a less specific version in the engines clause in package.lock?