allow https server to accept and pass thru alpn protocols to the underlying esp-tls server

components/esp_https_server/include/esp_https_server.h

@@ -99,6 +99,8 @@ struct httpd_ssl_config {
 
     void *ssl_userdata; /*!< user data to add to the ssl context  */
     esp_tls_handshake_callback cert_select_cb; /*!< Certificate selection callback to use */
+
+    const char** alpn_protos; /*!< Application protocols the server supports in order of prefernece. Used for negotiating during the TLS handshake, first one the client supports is selected. The data structure must live as long as the https server itself! */
 };
 
 typedef struct httpd_ssl_config httpd_ssl_config_t;

components/esp_https_server/src/https_server.c

@@ -212,6 +212,9 @@ static httpd_ssl_ctx_t *create_secure_context(const struct httpd_ssl_config *con
 
     cfg->userdata = config->ssl_userdata;
 
+
+    cfg->alpn_protos = config->alpn_protos;
+
 #if defined(CONFIG_ESP_TLS_SERVER_CERT_SELECT_HOOK)
     cfg->cert_select_cb = config->cert_select_cb;
 #endif