Add the firmware exercise. Not yet working

part3/emulator_exercise.md

part3/firmware/Scaler/hls/defines.h

part3/firmware/Scaler/hls/scaler.cpp

part3/firmware/Scaler/hls/synth.tcl

part3/firmware/payload/firmware/cfg/top_serenity.dep

part3/firmware/payload/firmware/hdl/NNWrapper.vhd

part3/firmware/payload/firmware/hdl/ScalerWrapper.vhd

part3/firmware/payload/firmware/hdl/emp_project_decl.vhd

part3/firmware/payload/firmware/hdl/payload.vhd

part3/make_scaler_hls.py

part3/serenity_exercise.md

part3/setup_fw_workspace.sh