Support setting cacheTag in Worker fetch

Hello,

It would be very useful if we could pass cacheTag when calling fetch which would set the ‘Cache-Tag’ header in the cache, without having to manually cache.put the modified response and wait for the cache save.

const cf: RequestInitCfProperties = {
  cacheKey: originRequestUri,
  // FEATURE REQUEST
  cacheTag: 'my-cache-tag'
};

const ttl = getCustomCacheableResourceTtl(originRequestUri);
if (ttl) {
  cf.cacheEverything = true;
  cf.cacheTtlByStatus = { '200-299': ttl, '304': ttl, '404': 1, '500-599': 0 };
}

let response = await fetch(originRequestUri, {
  method: request.method,
  headers: request.headers,
  body: request.body,
  cf,
});

https://api.cloudflare.com/#zone-purge-files-by-cache-tags,-host-or-prefix