Add aarch64 testing terraform config

When testing the linux aarch64 code on a real platform (AWS graviton),
it is a bit of a hassle walking through all the steps to instantiate,
configure, and then run the test suite. So I created a terraform
configuration that does it all for me (a la infrastructure as code).

Right now, the config is a too tailored to me (assumes the default
network policy allows inbound ssh and the ssh key is named "me"). But,
I'm a terraform noob, so I welcome implementation suggestions.

.gitignore

@@ -1,3 +1,11 @@
 **/target
 **/*.rs.bk
 Cargo.lock
+
+### Terraform ###
+# Local .terraform directories
+**/.terraform/*
+
+# .tfstate files
+*.tfstate
+*.tfstate.*

assets/aarch64.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+set -euxo pipefail
+
+terraform plan
+terraform apply -auto-approve
+public_ip=$(terraform output --raw public_ip)
+sleep 30
+ssh ec2-user@$public_ip "
+    sudo yum update -y &&
+    sudo yum groupinstall -y 'Development Tools' &&
+    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --profile minimal -y &&
+    source "\$HOME/.cargo/env" &&
+    git clone https://github.com/nickbabcock/highway-rs.git &&
+    cd highway-rs &&
+    cargo test"
+
+if [[ $? = 0 ]]; then
+  read -p "Test successful, preserve instance? (y/N): " -n 1 -r -t 300
+  if [[ ! $REPLY =~ ^[Yy]$ ]]; then
+    terraform destroy -auto-approve
+  fi
+else
+  echo "Test failed"
+fi

assets/aarch64.tf

@@ -0,0 +1,22 @@
+terraform {
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 5.0"
+    }
+  }
+}
+
+provider "aws" {
+  region = "us-east-1"
+}
+
+resource "aws_instance" "highway_aarch64" {
+  ami           = "ami-055859c8e0f361065"
+  instance_type = "t4g.small"
+  key_name      = "me"
+}
+
+output "public_ip" {
+  value = aws_instance.highway_aarch64.public_ip
+}