Expanding the set of hints

Currently the [`mev_sendBundle`](https://github.com/flashbots/mev-share/blob/main/specs/mev_sendBundle.md) and [`event-stream`](https://github.com/flashbots/mev-share/blob/main/specs/event-stream.md) APIs support sharing the following hints: `logs`, `calldata`, `function selector`, `contract address`.

One early idea is to also share the orderflow source (eg. the wallet or dapp a transaction originated from). This could reduce execution risk by distinguishing between informed and retail flow.

Searchers: What other hints would better enable you to search on programmably private orderflow from MEV-share?