feat(build): arm64 support

[the-wondersmith]

PR adds multi-arch / arm64 support to the linkerd dev tooling stack.

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Notes

There are a few stages that should be FROM apt-base as {stage name} but have been changed to FROM docker.io/library/rust:alpine as {stage name} (effectively). This is because the upstream sources these stages are pulling binaries from do not supply arm64 binaries. Luckily though, they're all rust codebases, so cargo install --git='repo url' --tag='existing version tag argument' takes care of the issue as a simple proof of concept.

The repositories in question are:

• j5j
• hokay
• cargo-action-fmt
• cargo-deny

There is an open (but as-of-yet-unmerged) PR to add arm64 builds to cargo-deny's releases.
PR #659 to cargo-deny was merged 2024-05-03.

The other three repos (j5j, hokay, and cargo-action-fmt) all belong to @olix0r and so hopefully won't be as much of an ordeal to add arm64 support to 😅.

IMPORTANT: while this PR should be entirely safe to merge without the altered stages being restored to their original FROM apt-base as {stage name} forms, they do impose a non-zero but realistically negligible amount of overhead to build times. If the decision is made to have the three repos mentioned above supply multi-arch binaries of their own, the only real changes to the Dockerfile that should persist should be the additions of the sed expressions that take care of formatting upstream urls to match the platform of the build target.

Screenshots

[the-wondersmith]

Closing this to get it off my list of open PRs, and because it doesn't seem like there's any interest in it outside of @kflynn 🫤. Please feel free to re-open it at your discretion though 🙂.