Add TLS handshake metrics atom proto

This CL adds a new Westworld pushed metric which counts the number of:

 1. Successful/failed handshakes
 2. Chosen protocol after handshake
 3. Chosen cipher suite after handshake
 4. Duration of the handshake, in milliseconds

Bug: 160345816
Test: m statsd_testdrive && ./out/host/linux-x86/bin/statsd_testdrive 317
Change-Id: I142a792c34dced6b0e27b867ed3a1d95249a5f7f