Add inspection for cgroup v2 CPU quota and period

[dagood]

I see this function, and essentially, I want to somehow use it in a Go application that runs inside a cpu-limited container so the app can understand its environment better:

cgroups/cgroup2/cpu.go

Line 56 in f1e92d8

func (c CPUMax) extractQuotaAndPeriod() (int64, uint64, error) {

cgroups/cgroup2/manager.go

Line 953 in f1e92d8

quota, period, err := resources.CPU.Max.extractQuotaAndPeriod()

I don't see any way to get at this information from the current public API.

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Is this something that would make sense to include in this module? The readme says "inspecting" cgroups is one of its goals, so my guess is that it would be a good feature.