Add Valkey support to ElastiCache CacheCluster

[flostadler]

Currently the ElastiCache CacheCluster resource does not support the Valkey engine. Instead it only supports redis and memcached.
Support for this is currently blocked on AWS APIs not accepting the engine type valkey in the CreateCacheCluster API call.

This upstream issue (hashicorp/terraform-provider-aws#39905) tracks support for this. Once it's released in the upstream terraform provider we can release it as part of pulumi-aws.

As a workaround you can use the ElastiCache ReplicationGroup resource to deploy Valkey cache cluster today. By setting numCacheClusters to one, it creates a single node cluster.

import * as aws from "@pulumi/aws";

const valkey = new aws.elasticache.ReplicationGroup("valkey-test", {
    description: "valkey cluster",
    nodeType: "cache.m4.large",
    numCacheClusters: 1,
    engine: "valkey",
    port: 6379,
});