`/usr/local/bin/brew` was the path for `x86_64-darwin`
`aarch64-darwin` uses `/opt/homebrew/bin/brew`
Use `${config.homebrew.brewPrefix}` to support both
See <c0d5b8c54d/modules/homebrew.nix (L561)>
Add `nixpkgs-cross-overlay` to substituters
Add `google-cloud-sdk` to `home.packages`
Remove comment (from old experiments) from `reo101-shell` HM module
Remove `pinentry-touchid` from `brew` packages (causing issues, no longer used)