add a feature into online workflow to generate Makefile from config file

This MR adds a feature into online workflow to generate Makefile from config file by running

gstlal_ll_inspiral_workflow init -c config.yml

Also, given the new mu sorting, I added sanity check function to see if sort-by or num-blah-bins options is missed or inproperly given in a config file upon the initialization of Config class.