feat(node): Wait for L2 safe head updates in DerivationActor

[clabby]

Overview

The derivation actor currently derives safe payload attributes, and sends them off to the engine actor to either be built or checked for equivalence with existing blocks via L1 consolidation (depending on if safe_head < unsafe_head.)

When attributes are sent off, the pipeline must wait to continue processing payloads until the L2 safe head has advanced. This synchronization step should happen here:

kona/crates/node/service/src/actors/derivation.rs

Line 201 in 3f70082

self.attributes_out.send(payload_attrs).map_err(Box::new)?;