feat: handle PiecesAddedV2 event

PR https://github.com/FilOzone/pdp/pull/300 introduces a more compact representation of the PiecesAdded event.
Indexers should start handling the new event while keeping the old event for compatibility with historical state.
Please wait for https://github.com/FilOzone/pdp/pull/300 to be merged.

ref https://github.com/FilOzone/pdp/issues/302