rust: Support for rust enable builds

[mkchauras]

Enabling ppc64le rust build support.

[mpe]

This is deploying here https://github.com/linuxppc/ci-scripts/actions/runs/23417882226

Once that completes the docker images will be available to pull.

[mpe-tt]

OK that went badly 😊

The changes to the Dockerfile don't work on the old Ubuntu versions.

There's existing logic in build/ubuntu/packages.sh for selecting different packages based on the Ubuntu version, you should be able to use that to make the Rust packages only install on newer versions.

But you'll also need to make the rust install steps conditional.

I think the best solution is to create a new script, install-rust.sh in ubuntu and have it only run the curl/rustup/cargo commands on 24.04 or later. It should be OK to leave the Rust related ENV settings in the Dockerfile even if Rust is not installed.

[mkchauras]

Ohooo
Letme fix these and then i'll resend the whole pull request again.
I'll create a new script install-rust.sh via rustup. No package manager this time.