h3-proxy: fixes around H3 proxy

code:
- less exception handling in existing code
- true ip happy eyeballing
- enable certificate verification
- cf-h2-proxy: abort connection when server closed connection

tests:
- remove all --insecure and --proxy-insecure args
- make session reuse test_60_12 a working one
- resolve port conflicts between h2o and nghttpx
- use proxy args better
- make test_60_06 run shorter
- kill h2o at the end of tests, normal stop takes too long

Ref: 59213f8248 #21789
Follow-up to e78b1b3ecc #21153

Closes #21798

lib/http_proxy.c

@@ -753,8 +753,8 @@ struct Curl_cftype Curl_cft_http_proxy = {
 CURLcode Curl_cf_http_proxy_insert_after(struct Curl_cfilter *cf_at,
                                          struct Curl_easy *data,
                                          struct Curl_peer *dest,
-                                         uint8_t proxytype,
-                                         bool udp_tunnel)
+                                         uint8_t transport,
+                                         uint8_t proxytype)
 {
   struct Curl_cfilter *cf;
   struct cf_proxy_ctx *ctx = NULL;
@@ -771,7 +771,7 @@ CURLcode Curl_cf_http_proxy_insert_after(struct Curl_cfilter *cf_at,
   }
   Curl_peer_link(&ctx->dest, dest);
   ctx->proxytype = proxytype;
-  ctx->udp_tunnel = udp_tunnel;
+  ctx->udp_tunnel = (transport == TRNSPRT_QUIC);
 
   result = Curl_cf_create(&cf, &Curl_cft_http_proxy, ctx);
   if(result)
@@ -784,4 +784,14 @@ out:
   return result;
 }
 
+uint8_t Curl_http_proxy_transport(uint8_t proxytype)
+{
+  switch(proxytype) {
+  case CURLPROXY_HTTPS3:
+    return TRNSPRT_QUIC;
+  default:
+    return TRNSPRT_TCP;
+  }
+}
+
 #endif /* !CURL_DISABLE_HTTP && !CURL_DISABLE_PROXY */