Allow multiple vtxos per tree leaf #881
Description
If an intent specifies multiple vtxo outputs (including an op_return!), by default we should create them on a single batch tree leaf to reduce the size of the tree in a natural optimization. This also allows us to support Arkade Assets due to the op return support.
We must ensure that this change is backwards compatible for clients.
Undecided and out of scope for initial version: allow a config through the intent message to let users opt-out of this feature.