Include ANR duration & start time in the ANR report file

ANR duration (ms) added as "Timeout: ...."
ANR start uptime (ms) added as "TimeoutStart: ..."

The rationale behind adding these is so that downstream debugging tools know when the unresponsive period started and how long it lasted for. Since the platform can dynamically extend timeouts (and OEMs can pick different timeouts) we can't depend on heuristics like "broadcast ANR timeout is always 10/60 seconds", etc.

Test: Triggered some ANRs & checked files in /data/anr
Bug: 409760497
Flag: EXEMPT small change to error logging

Change-Id: I58371b554de8c655d0671a6530a86f27aa78fd1a