feat(chain-state): notify about new safe/finalized only if modified

[shekhirin]

ForkChoiceSubscriptions is expected to be triggered only on new safe/finalized headers, but we in fact notify the subscribers every time we get an FCU, even if it's the same safe/finalized hash.

reth/crates/chain-state/src/notifications.rs

Lines 145 to 163 in 86f12b7

	/// A trait that allows to register to fork choice related events
	/// and get notified when a new fork choice is available.
	pub trait ForkChoiceSubscriptions: Send + Sync {
	/// Get notified when a new safe block of the chain is selected.
	fn subscribe_safe_block(&self) -> ForkChoiceNotifications;
	/// Get notified when a new finalized block of the chain is selected.
	fn subscribe_finalized_block(&self) -> ForkChoiceNotifications;
	/// Convenience method to get a stream of the new safe blocks of the chain.
	fn safe_block_stream(&self) -> ForkChoiceStream<SealedHeader> {
	ForkChoiceStream::new(self.subscribe_safe_block().0)
	}
	/// Convenience method to get a stream of the new finalized blocks of the chain.
	fn finalized_block_stream(&self) -> ForkChoiceStream<SealedHeader> {
	ForkChoiceStream::new(self.subscribe_finalized_block().0)
	}
	}