convert license headers to SPDX

Includes license review of 3rd-party files, adding missing upstream
headers, and moving the UNSW OZPLB license into its own file rather
than replicating it in the header.

CMake: Updated generation of the simulation script

Refactored the generation of the simulation script. This change
introduces an implementation of the simulation script in python.
The python script is templated with CMake variables
(through configure_file). Bringing the script to python makes
running simulate more configurable by the caller
e.g overwrite or append specific flags.