Add support for custrom args in user-defined modules

examples/dem_sd.py

examples/main.cpp

src/pairs/analysis/devices.py

src/pairs/analysis/modules.py

src/pairs/code_gen/cgen.py

src/pairs/ir/declaration.py

src/pairs/ir/device.py

src/pairs/ir/functions.py

src/pairs/ir/kernel.py

src/pairs/ir/module.py

src/pairs/ir/parameters.py

src/pairs/mapping/funcs.py

src/pairs/sim/simulation.py