split up events target and move events.cpp to separate target
split up events target and move events.cpp to separate target

Summary: only events.cpp required by plugin_sdk, everything else is not necessary

Reviewed By: marekcirkos

Differential Revision: D14131365

fbshipit-source-id: 18e101b3e549d8403aa22ee3d5a5fadd2b296c82

hackgnar/osquery,hackgnar/osquery,hackgnar/osquery