Function any_ironwood_tree 

pub fn any_ironwood_tree<'a, C: AsRef<Chain> + 'a>(
    chains: impl Iterator<Item = &'a C>,
    db: &ZebraDb,
    hash: Hash,
) -> Option<Arc<NoteCommitmentTree>>

Returns the Ironwood NoteCommitmentTree for the block with hash, if it exists in any of the non-finalized chains or finalized db.

Unlike ironwood_tree, this checks every non-finalized chain (best chain first, then side chains), so it is immune to reorgs that move a block from the best chain onto a still-retained side chain.

Ironwood reuses the Orchard note commitment tree type, in a separate tree.