* op-challenger: Add keccak sponge impl

Provides a StateMatrix implementation that can calculate the state commitment after each permutation.

* op-challenger: Add randomly generated reference tests.

* op-challenger: Split library code to a separate file.

* op-challenger: Expose PackState method

* op-challenger: Add reader based method to make it easier to split up data correctly.

* op-challenger: Fix fuzz makefile target.

* op-challenger: Include full license to comply with source distribution requirements.