Add polling for getBlock and emit `block` event whenever a new block is added on Starknet

[dhruvkelawala]

To be implemented on Provider

[janek26]

this sounds like a very heavy method.. I don't like polling very much. If implemented with polling then it should be lazy.

[rzmahmood]

  private async waitTillBlock(blockNumber: number) {
    let latestBlockNumber;
    while (latestBlockNumber !== blockNumber) {
      try {
        latestBlockNumber = await this.provider.getBlockNumber();
        this.log.info(`waiting till block`, { waitingFor: blockNumber, latest: latestBlockNumber });
      } catch (e) {
        this.log.warn('failed to get block number, retrying', {
          err: e
        });
      }
      await Promise.delay(10000);
    }
  }

[tabaktoni]

I don't know if are there use cases for this but as a method, we can have it in both providers, I see no reason for this not to be implemented. Ideally, this would be implemented true WebSocket for RPC but until we get to Nodes with it we can provide this? @rzmahmood Can you create PR for this? Or if not we can close the Issue until someone ask for it?

[ivpavici]

Closing in favour of https://github.com/0xs34n/starknet.js/issues/112 ...since support for WebSockets should become a reality soon on Pathfinder