Process and verify merkle proofs (and multiproof) with custom hash function (#4887)

Co-authored-by: ernestognw <ernestognw@gmail.com>

scripts/generate/templates/MerkleProof.opts.js

@@ -0,0 +1,11 @@
+const { product } = require('../../helpers');
+
+const OPTS = product(
+  [
+    { suffix: '', location: 'memory' },
+    { suffix: 'Calldata', location: 'calldata' },
+  ],
+  [{ visibility: 'pure' }, { visibility: 'view', hash: 'hasher' }],
+).map(objs => Object.assign({}, ...objs));
+
+module.exports = { OPTS };