[DAWN] Sending and Displaying Latency Data

[lawrencechen14]

In order to get accurate latency data, we need to coordinate with Runtime to send timestamps accordingly so that we can subtract with our timestamp to display the latency in Dawn.

• Receive TCP packet with header 5 from Runtime that includes a timestamp, and find the difference in time with our timestamp and theirs.
• Store this difference and display it in Dawn somewhere, which is perhaps can be triggered with a button.
• Send TCP packet with header 6 back to Runtime with our timestamp.

Linked to #715