Add new API to stop mqtt client asynchronous in the background (IDFGH-16504)#315

0xFEEDC0DE64 wants to merge 1 commit intoespressif:masterespressif/esp-mqtt:masterfrom

0xFEEDC0DE64:async_stop0xFEEDC0DE64/esp-mqtt:async_stopCopy head branch name to clipboard