simplify function signature

[knightron0]

currently, the solution and reference solution signatures are different (this was done to make casting easier in the short term) but it's creating some ambiguity now. even though a lot of reference solutions don't require some of the parameters:

• get rid of get_extra_params all together and have create_test_case return all parameters needed for the function
• this will avoid the mess of doing *(input_ptrs + [output_ptr] + extra_params) here
• typecasting can be cleaned up

this would require edits to runner.py as well for integration