Report RSS and the commit charge on Windows

[hsbt]

On Windows, rss, maxrss and the RSS samples taken after each iteration are always 0, because there is no /proc, ps or getrusage to read them from.

This reports the working set and its peak from GetProcessMemoryInfo as RSS and MAXRSS. It also records the commit charge and its peak as commit_charge and peak_commit_charge, since private allocations on Windows show up there more than in the working set.

Generated with Claude Code

[k0kubun]

Can we define Windows-only modules (and ideally methods as well) only when it's Windows? Unlike what's executed inside run_benchmarks.rb, what runs in harness/harness-common.rb directly impacts the benchmark target's performance, such as the size of allocated memory.

Combined with #549 (which may not need to be done inside harness-common.rb in the first place), I see a couple of modules and several methods that don't need to be defined in non-Windows platforms. Maybe we can define all of them under an is_windows guard.