settings_um: Use live config

Add a new JSON out target to pull the live config data and use that for
the usermod settings page.  Should fix issues with outdated contents.

Author: willmmiles

wled00/data/settings_um.htm

@@ -13,7 +13,7 @@
 	function S() {
 		getLoc();
 		// load settings and insert values into DOM
-		fetch(getURL('/cfg.json'), {
+		fetch(getURL('/json/cfg'), {
 			method: 'get'
 		})
 		.then(res => {

wled00/json.cpp

@@ -1028,7 +1028,7 @@ class LockedJsonResponse: public AsyncJsonResponse {
 void serveJson(AsyncWebServerRequest* request)
 {
   enum class json_target {
-    all, state, info, state_info, nodes, effects, palettes, fxdata, networks
+    all, state, info, state_info, nodes, effects, palettes, fxdata, networks, config
   };
   json_target subJson = json_target::all;
 
@@ -1041,6 +1041,7 @@ void serveJson(AsyncWebServerRequest* request)
   else if (url.indexOf(F("palx"))  > 0) subJson = json_target::palettes;
   else if (url.indexOf(F("fxda"))  > 0) subJson = json_target::fxdata;
   else if (url.indexOf(F("net"))   > 0) subJson = json_target::networks;
+  else if (url.indexOf(F("cfg"))   > 0) subJson = json_target::config;
   #ifdef WLED_ENABLE_JSONLIVE
   else if (url.indexOf("live")     > 0) {
     serveLiveLeds(request);
@@ -1051,9 +1052,6 @@ void serveJson(AsyncWebServerRequest* request)
     request->send_P(200, FPSTR(CONTENT_TYPE_JSON), JSON_palette_names);
     return;
   }
-  else if (url.indexOf(F("cfg")) > 0 && handleFileRead(request, F("/cfg.json"))) {
-    return;
-  }
   else if (url.length() > 6) { //not just /json
     serveJsonError(request, 501, ERR_NOT_IMPL);
     return;
@@ -1085,6 +1083,8 @@ void serveJson(AsyncWebServerRequest* request)
       serializeModeData(lDoc); break;
     case json_target::networks:
       serializeNetworks(lDoc); break;
+    case json_target::config:
+      serializeConfig(lDoc); break;
     case json_target::state_info:
     case json_target::all:
       JsonObject state = lDoc.createNestedObject("state");