Support for ARM (arm64) architecture?

## Problem

Most of our developer laptops and some of our Kubernetes nodes now run on `arm64` architecture (`aarch64` on the MacBooks), but the `auto-linux` and `auto-macos` assets, as of [v11.1.1](https://github.com/intuit/auto/releases/tag/v11.1.1), are only available for `x86-64` (a.k.a. `amd64`) architecture.

This means we can't use `auto` everywhere we'd like, which for us and I suspect for many users is either an impediment to using `auto` or to switching architectures.

PS: Linux has supported `arm64` for about a decade, and Apple since 2020 (and has begun winding down support of `x86-64`/`amd64`). I do not know about Windows.

## Proposed solution

Build and publish assets for the `arm64` architecture for Linux and MacOS.

## Alternatives

We could build them from source code for our own use, but it seems like the `auto` team would want to do this anyway.

Start by tracing how the auto-linux and auto-macos assets are built and published, including the architecture matrix used for releases. Done means arm64 assets are built and published for both Linux and macOS, with the release process still supporting the existing x86-64 assets.

Written by the indexing model from the issue text.