Allow subscribing to safe block changes

[cohuebn]

Describe the Feature

Overview

A provider can emit events to facilitate observing interesting things happening on chain. It'd be really nice if we could subscribe to the latest safe block. See #3068 for more details. This would allow applications to respond only when the safe block changes which is a good happy-medium between pending (higher likelihood of reorganization) and finalized (takes up to 15 minutes on networks like Sepolia)

Specific request

• A new safe event is emitted when the latest safe block becomes available

Code Example

// Typescript example using Ethereum JSON RPC provider
const provider = new JsonRpcProvider("https://rpc.ankr.com/eth");
provider.on("safe", (blockNumber: number) => {
  console.log(`Received new safe block number: ${blockNumber}`);
});

[ricmoo]

Added in 6.9.0.

You can now use:

// Fire the event whenever the safe block changes
provider.on("safe", (blockNumbder) => { ... });

// Fire the event whenever the finalized block changes
provider.on("finalized", (blockNumbder) => { ... });

Thanks for the suggestions! :)