refactor(Protogalaxy): Move state out of Instances

[codygunton]

The main goal of this PR, which is achieved, is to move all move all data except the _data array out of ProverInstances. I do additional cleanup:

• Use constructors for pow polys rather than a void type function to update the state.
• Delete commented out higher folding test, which I had been maintaining in commented out form
• Move ProtogalaxyProofConstructionState def into ProtogalaxyProver
• More idiomatic folding of relation parameters (loop over a zip of getters)

[ledwards2225]

This looks good too