Support more types of redistribution

The most basic form of redistribution involves transferring a single refund to the address specified in the validity condition of a mev-share bundle. But validity conditions could also support more complex types of redistribution.

One idea is to split proceeds across multiple recipients (with different % for each recipient). This can be handled by adding a new entry to the refundConfig for the new recipient.

Orderflow providers: What other ideas or requests do you have for improving the UX around redistribution? See also https://github.com/flashbots/mev-share/issues/1.