provide more flexible WatchPidFields API

[rootfs]

I am using go-dcgm to estimate power consumption of processes running in MIG device. The current pid watch function watchPidFields doesn't track the MIG devices.

Would it be possible to create yet another API to pass group.handle directly? So caller can create device groups that consist MIG and call the dcgm API to watch pid.

A hypothetical prototype is like the following:

func WatchPidFieldsWithGroup(updateFreq, maxKeepAge time.Duration, maxKeepSamples int, groupId GroupHandle) error {
	result := C.dcgmWatchPidFields(handle.handle, groupId.handle, C.longlong(updateFreq.Microseconds()), C.double(maxKeepAge.Seconds()), C.int(maxKeepSamples))
	if err := errorString(result); err != nil {
		return &DcgmError{msg: C.GoString(C.errorString(result)), Code: result}
	}
	_ = UpdateAllFields()
	return nil
}

[nvvfedorov]

@rootfs , Thank you for submitting the issue. We accept PRs if you have a good solution.

[rootfs]

@nvvfedorov that sounds good, i'll test it locally and if this works, i'll submit a PR, thanks