Simplify code in assemble_shares

[ggutoski]

In file vid/src/advz.rs in function assemble_shares we have the following code snippet:

jellyfish/vid/src/advz.rs

Lines 915 to 932 in 92714a4

	let mut shares = Vec::with_capacity(self.num_storage_nodes as usize);
	let mut evals = Vec::with_capacity(num_of_polys * self.multiplicity as usize);
	let mut proofs = Vec::with_capacity(self.multiplicity as usize);
	let mut index = 0;
	for i in 0..code_word_size {
	evals.extend(all_storage_node_evals[i].iter());
	proofs.push(aggregate_proofs[i].clone());
	if (i + 1) % self.multiplicity as usize == 0 {
	shares.push(Share {
	index,
	evals: mem::take(&mut evals),
	aggregate_proofs: mem::take(&mut proofs),
	evals_proof: all_evals_commit // TODO: check MT lookup for each index
	.lookup(KzgEvalsMerkleTreeIndex::<E, H>::from(index as u64))
	.expect_ok()
	.map_err(vid)?
	.1,
	});

Here evals, proofs are mutable Vecs and we use mem::take to initialize a Share struct. This seems unnecessarily complex and obfuscated to me.

We should be able to eliminate evals, proofs and simply move the relevant data directly into Share::evals, Share::evals_proof something like

evals: all_storage_node_evals[i],
evals_proof: aggregate_proofs[i],

Probably need to loop over a more idiomatic iterator instead of using i to index into these Vecs.