[Structure] Refactor repo

[ngundotra]

indexer/
  plerkle/
  docker/
  nft_api/
  nft_ingester/
  ...
programs/
  ...
  gummyroll/
    src/
      state/
        merkle_roll.rs, refactor this into separate rust package that can be published separately
concurrent_merkle_tree/
  -> this should be where merkle tree functions live, so easier to test & audit
.archive/
  -> make this a dotfile