Instrument execution with start time and end time

- Add start time and end time of each execution
- Show execution time of leaf in each test

Bug: 140677693
Test: manual test
Change-Id: Ib2bb30add4f3a22f19562f9b02f6ec7d689af901
Merged-In: Ib2bb30add4f3a22f19562f9b02f6ec7d689af901
8 files changed