monitor: Add latency when decoding BT_HCI_EVT_NUM_COMPLETED_PACKETS

monitor: Add latency when decoding BT_HCI_EVT_NUM_COMPLETED_PACKETS

This adds latency, min-max, and median information when decoding
BT_HCI_EVT_NUM_COMPLETED_PACKETS so it works similarly to --analyze:

> HCI Event: Number of Completed Packets (0x13) plen 5
        Num handles: 1
        Handle: 256 Address: XX:XX:XX:XX:XX:XX
        Count: 1
        Latency: 23 msec (2-66 msec ~19 msec)