Create command line option on wperf to use the PID instead of the image name

[PrzemekWirkus]

Cloned from: https://linaro.atlassian.net/browse/WPERF-550

Right now the sample command requires the user to input the image name to track down a process. Users have requested that we use the PID instead.

In order to get this implemented we need to change FindProcess on process_api.cpp to support using the PID. This should be fairly simple as the OpenProcess (OpenProcess function (processthreadsapi.h) - Win32 apps | Microsoft Learn) function actually requires the PID and most of the FindProcess function is to actually find out what is the PID.