Decommits as tx outputs, not separate L2 requests

[GeorgeFlerovsky]

If L1 and L2 utxos are distinguished by their network ID in address, then de-committing can just be a result of an L2 transaction that outputs a utxo with an L1 address.

Pros:

• The same L2 tx can partially decommit some funds while keeping the rest on L2.

Cons:

• More difficult to handle intermingled tx/decommit logic with minimal modification to Cardano ledger rules.

How:

1. Validate the tx while disabling any checks of network ID in output addresses.
2. If the tx validates, partition its outputs into those staying on L2 and those departing to L1.