Previously, reset over USB CDC was done by calling esp_restart from
an interrupt handler. This works only until some restart hook function
is registered using esp_register_shutdown_handler, and the hook
function tries to do something that isn’t allowed in an interrupt
handler. One such case is with Wi-Fi. When Wi-Fi driver is installed,
it registers esp_wifi_stop as a shutdown handler function. However
esp_wifi_stop cannot be called from an ISR, and hence we shouldn’t
call esp_restart from an ISR either.
This commit modifies USB CDC driver to call esp_restart by posting it
to esp_timer task.
Closes https://github.com/espressif/esp-idf/issues/7404
