fix "no pre-built binaries" error for aarch64, use x86_64 via rosetta

[nilslice]

Adds support for installing binary deps (wasm-opt, etc) on a aarch64-apple-darwin target, via usage of the x86_64 binary run through the Apple-provided Rosetta instruction translator. As long as Rosetta 2 is installed on the target Apple device, all downloaded binaries will be executed using it automatically.

More info on Rosetta 2: https://support.apple.com/en-us/HT211861

closes: #952

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• You have the latest version of rustfmt installed
• You ran cargo fmt on the code base before submitting
• You reference which issue is being closed in the PR text

[nilslice]

looks like appveyor ci check is failing here:

stderr=```[INFO]: Installing cargo-generate...
error: the `--vers` provided, `latest`, is not a valid semver version: cannot parse 'latest' as a semver
Error: Installing cargo-generate with cargo
Caused by: failed to execute `cargo install`: exited with exit code: 101
  full command: "cargo" "install" "--force" "cargo-generate" "--version" "latest" "--root" "C:\\projects\\wasm-pack-071k0\\target\\test_cache\\.cargo-generate-cargo-install-latest"

doesn't like "latest" as a version, so we may need to pull the semver compliant version.

[nilslice]

In a different failing test, an attempt is made to download a pre-built binary at this URL:
https://github.com/ashleygwilliams/cargo-generate/releases/download/v0.6.1/cargo-generate-v0.6.1-x86_64-pc-windows-msvc.tar (which would be redirected to the new org cargo-generate)

The issue is that releases haven't contained these assets since Sept. 2020 (v0.5.1, https://github.com/cargo-generate/cargo-generate/tags)

Was there a reason builds were excluded from the releases since then?