Traversable Trie Advanced Data Layout

[nasdf]

Traversal of MMPTs requires logic that cannot be done within standard IPLD selectors.
Creating a simple ADL for trie nodes will enable much simpler IPLD queries.

• Select transaction <tx-root>/<rlp-index>
• Select account <state-root>/<keccak256-address>
• Select storage <storage-root>/<keccak256-slot>

The ADL would transform TrieBranchNode, TrieExtensionNode, and TrieLeafNode types.
The proposed ADL could take the following form.

type TraversableTrie struct {
    Child0 nullable &TraversableTrie
    Child1 nullable &TraversableTrie
    Child2 nullable &TraversableTrie
    Child3 nullable &TraversableTrie
    Child4 nullable &TraversableTrie
    Child5 nullable &TraversableTrie
    Child6 nullable &TraversableTrie
    Child7 nullable &TraversableTrie
    Child8 nullable &TraversableTrie
    Child9 nullable &TraversableTrie
    ChildA nullable &TraversableTrie
    ChildB nullable &TraversableTrie
    ChildC nullable &TraversableTrie
    ChildD nullable &TraversableTrie
    ChildE nullable &TraversableTrie
    ChildF nullable &TraversableTrie
    Value  nullable Value
    PartialPath nullable Bytes
}