🔱: [acme] sync upgrade with 4 commits [trident-sync]

Example for on-demand tls-alpn-01
Example disclaimer, fallback cert
Replace CircleCI with GitHub Actions

packages/core/acme-client/examples/tls-alpn-01/nginx.conf

@@ -0,0 +1,19 @@
+##
+# HTTPS server
+# - Send to ALPN responder port 4444 if protocol is acme-tls/1
+# - Default to HTTPS backend port 4443
+##
+
+stream {
+  map $ssl_preread_alpn_protocols $tls_port {
+    ~\bacme-tls/1\b 4444;
+    default 4443;
+  }
+
+  server {
+    listen 443;
+    listen [::]:443;
+    proxy_pass 127.0.0.1:$tls_port;
+    ssl_preread on;
+  }
+}