alexa: fix device discovery / state callback (#2388)

alexa device discovery/state calls use URL of type
/api/hash_id_key_whatever/lights

This is blocked when API is disabled and fails
also when http API is enabled because no apikey is
sent by amazon calls

Don't try to use the http api for alexa calls.
Responses for alexa are done by fauxmoesp lib,
so there's no need for the http api call.

code/espurna/api.cpp

@@ -224,6 +224,12 @@ bool _apiRequestCallback(AsyncWebServerRequest* request) {
     }
 
     if (!url.startsWith("/api/")) return false;
+
+// [alexa] don't call the http api -> response for alexa is done by fauxmoesp lib
+#if ALEXA_SUPPORT
+    if (url.indexOf("/lights") > 14 ) return false;
+#endif
+
     if (!apiAuthenticate(request)) return false;
 
     return _apiDispatchRequest(url, request);