Move functions that read process data into LinuxProcess.c
and change flow from a monolithic `ProcessList_scan ->
ProcessList_goThroughEntries` into the following:

```
ProcessList_scan -> (Linux)ProcessList_goThroughEntries ->
ProcessList_scanProcess -> (Linux)Process_update
```

This will allow hooking plugins into the scanning
process.

Other platforms need to be similarly reworked.