[wip] trie: enable Commit for stacktrie

[gballet]

No description provided.

[holiman]

As an alternative, you let the outer world provide a hasher, which is reused by this stacktrie. Something like :

hasker := crypto.NewKeccakState()
st := NewStacktrie( hasher)
for {
  st.TryUpdate(key, value)
}
h := st.Hash()

Then you wouldn't need the pooling, but you'd instead need to separate between the public StackTrie and the internal stackTrie node representations.

[holiman]

This can be closed now, I think.. ?
Deprecated by #21407