Convert BusManager class to namespace

- use unique_ptr/make_unique for busses

wled00/cfg.cpp

@@ -876,8 +876,7 @@ void serializeConfig() {
   const ColorOrderMap& com = BusManager::getColorOrderMap();
   for (size_t s = 0; s < com.count(); s++) {
     const ColorOrderMapEntry *entry = com.get(s);
-    if (!entry) break;
-
+    if (!entry || !entry->len) break;
     JsonObject co = hw_com.createNestedObject();
     co["start"] = entry->start;
     co["len"] = entry->len;