RainMaker library: Minor changes (#5092)

- Use Serial.print instead of log_i for QR code helper information,
  so that it is always printed by default.
- Expose the RainMaker factory reset and wifi reset APIs.
- Simplify example to have only a Switch device. Create another example for custom device.
- Enable push button based Factory reset and Wi-Fi reset.
- Added support for the TimeZone service.
- Moved API doc to RainMaker library's top level README.
- Other minor doc changes.

libraries/RainMaker/src/RMaker.cpp

@@ -92,6 +92,15 @@ esp_err_t RMakerClass::enableSchedule()
     return err;
 }
 
+esp_err_t RMakerClass::enableTZService()
+{
+    err = esp_rmaker_timezone_service_enable();
+    if(err != ESP_OK) {
+        log_e("Timezone service enable failed");
+    }
+    return err;
+}
+
 esp_err_t RMakerClass::enableOTA(ota_type_t type, const char *cert)
 {
     esp_rmaker_ota_config_t ota_config;
@@ -104,4 +113,4 @@ esp_err_t RMakerClass::enableOTA(ota_type_t type, const char *cert)
 }
 
 RMakerClass RMaker;
-#endif
+#endif