Add wakeup attribution to trace

Adding two events to trace:
- Log the timestamp and the raw reason provided by the kernel when the
  wakeup happens.
- Log the attribution once it is computed by CpuWakeupStats. This
  attribution will also start with the timestamp of the wakeup.
The timestamps are added to both events to allow easy association.

Test: Manually, by collecting a trace containing a wakeup.

Bug: 269169212
Change-Id: If61ceef6af591b5a050b931a35b512837383fe69