lib: make resolving HTTPS DNS records reliable:

- allow to specify when they are wanted on starting a resolve
- match dns cache entries accordingly. An entry which never
  tried to get HTTPS-RRs is no answer for a resolve that wants
  it.
- fix late arrivals of resolve answers to match the "async"
  records that started them - if it still exists.
- provide for multiple "async" resolves in a transfer at the
  same time. We may need to resolve an IP interface while the
  main connection resolve has not finished yet.
- allow lookup of HTTPS-RR information as soon as it is
  available, even if A/AAAA queries are still ongoing.

For this, the "async" infrastructure is changed:

- Defined bits for DNS queries `CURL_DNSQ_A`, `CURL_DNSQ_AAAA`
  and `CURL_DNSQ_HTTPS`. These replace `ip_version` which says
  nothing about HTTPS.
  Use them in dns cache entries for matching.
- enhance the `async->id` to be a unique `uint32_t` for
  resolves inside one multi. This is weak, as the id may
  wrap around. However it is combined with the `mid` of
  the easy handle, making collisions highly unlikely.
  `data->state.async` is only accessed in few places where
  the mid/async-id match is performed.
- vtls: for ECH supporting TLS backends (openssl, rustls, wolfssl),
  retrieve the HTTPS-RR information from the dns connection filter.
  Delay the connect if the HTTPS-RR is needed, but has not
  been resolved yet.

The implementation of all this is complete for the threaded
resolver. c-ares resolver and DoH do not take advantage of
all new async features yet. To be done in separate PRs.

Details:

c-ares: cleanup settings and initialisation. Any ares channel
is only being created on starting a resolve and propagating
operations in setopt.c to the channel are not helpful.

Changed threaded+ares pollset handling so that they do not
overwrite each others `ASYNC_NAME` timeouts.

Add trace name 'threads' for tracing thread queue and
pool used by threaded resolver.

Closes #21175

lib/thrdqueue.c

@@ -380,27 +380,27 @@ CURLcode Curl_thrdq_set_props(struct curl_thrdq *tqueue,
 
 #ifdef CURLVERBOSE
 void Curl_thrdq_trace(struct curl_thrdq *tqueue,
-                      struct Curl_easy *data,
-                      struct curl_trc_feat *feat)
+                      struct Curl_easy *data)
 {
+  struct curl_trc_feat *feat = &Curl_trc_feat_threads;
   if(Curl_trc_ft_is_verbose(data, feat)) {
     struct Curl_llist_node *e;
     struct thrdq_item *qitem;
 
-    Curl_thrdpool_trace(tqueue->tpool, data, feat);
+    Curl_thrdpool_trace(tqueue->tpool, data);
     Curl_mutex_acquire(&tqueue->lock);
     if(!Curl_llist_count(&tqueue->sendq) &&
        !Curl_llist_count(&tqueue->recvq)) {
-      Curl_trc_feat_infof(data, feat, "[%s] [QUEUE] empty", tqueue->name);
+      Curl_trc_feat_infof(data, feat, "[TQUEUE-%s] empty", tqueue->name);
     }
     for(e = Curl_llist_head(&tqueue->sendq); e; e = Curl_node_next(e)) {
       qitem = Curl_node_elem(e);
-      Curl_trc_feat_infof(data, feat, "[%s] [QUEUE] in: %s",
+      Curl_trc_feat_infof(data, feat, "[TQUEUE-%s] in: %s",
                           tqueue->name, qitem->description);
     }
     for(e = Curl_llist_head(&tqueue->recvq); e; e = Curl_node_next(e)) {
       qitem = Curl_node_elem(e);
-      Curl_trc_feat_infof(data, feat, "[%s] [QUEUE] out: %s",
+      Curl_trc_feat_infof(data, feat, "[TQUEUE-%s] out: %s",
                           tqueue->name, qitem->description);
     }
     Curl_mutex_release(&tqueue->lock);