Config option to disable target reset on serial break

Hi DAPLINK developers:

I am Alex from NXP.

In file: https://github.com/ARMmbed/DAPLink/blob/master/source/daplink/usb2uart/usbd_user_cdc_acm.c

I noticed that USB_CDC_ACM_SendBreak Implementation may not correct, it should not be reset target MCU:

```c
static U32 start_break_time = 0;
int32_t USBD_CDC_ACM_SendBreak(uint16_t dur)
{
uint32_t end_break_time;

// reset and send the unique id over CDC
if (dur != 0) {
start_break_time = os_time_get();
target_set_state(RESET_HOLD);
} else {
end_break_time = os_time_get();

// long reset -> send uID over serial (300 -> break > 3s)
if ((end_break_time - start_break_time) >= (300)) {
main_reset_target(1);
} else {
main_reset_target(0);
}
}

return (1);
}
```

see: https://man7.org/linux/man-pages/man3/tcsendbreak.3p.html

Read source/daplink/usb2uart/usbd_user_cdc_acm.c, especially USBD_CDC_ACM_SendBreak, and trace how target reset is configured. Define the configuration path for disabling target reset on serial break, then verify that the setting preserves reset behavior when enabled and prevents it when disabled.

Written by the indexing model from the issue text.