[Windows] Implement support for the `cpu-clock` perf pseudo-counter

The Linux perf tool has a counter called cpu-clock which is basically just the total time the process was running on each thread. (As a simple example, suppose a process runs for 3 seconds on 1 core and, at the same time, 1 second on another core, then the cpu-clock would read 4 seconds)

This counter isn't backed by a hardware performance counter, rather it is a metric derived from some hardware performance counters and as such, doesn't exist on Windows. However, we can replicate the counter ourselves.

To do that, we'll need to keep track of the times each thread we care about spends active on a core and sum the total times together. We may be able to use the Timestamp data already collected in the trace file for this purpose or we may need to use the Time (or TimerFixed?) PMC.

https://github.com/rust-lang/rustc-perf/blob/c648f394e7228a9676b9cbc4b46974fea7f9c14d/collector/src/etw_parser.rs#L384-L388

https://github.com/rust-lang/rustc-perf/blob/c648f394e7228a9676b9cbc4b46974fea7f9c14d/collector/src/etw_parser.rs#L398-L399

After this is implemented, the detailed self-profile query results page should show reasonable numbers in the total "Time %" cell.

Start by reading the linked sections of collector/src/etw_parser.rs around lines 384-388 and 398-399, then trace how the Windows ETW data reaches the detailed self-profile query results page. Determine how the existing Timestamp, Time, or TimerFixed data relates to per-thread active time. Done means the page shows reasonable values in the total "Time %" cell for Windows profiles.