feat: transaction simulation endpoint

[ncitron]

Supporting transaction simulation would be an awesome usecase for Helios. We need to think about what exactly this endpoint would look like.

The simplest case would be to have the same interface as eth_call but returning a receipt for the simulated transaction. Two additional features we could add is showing a state diff from the transaction, or even to support allowing arbitrary rpc calls on the post transaction state.

[shazow]

Related brainstorming thread in case it's useful later: https://warpcast.com/ncitron.eth/0x4238de4f

[TateGunning]

Nice work! Many variables to consider.

Perhaps more complex cases involve greater decentralisation contingent or security detail depending, or applied analytics.

Mutual respect and disclosure of raw info or tasteful privacy.

Idea-flow possibilities: origination, consent, scope model promoting user awareness best practice and or training module, mental status, biographics, attempt versus equal benefit, time mechanisms, early observatory clicks, too often repetitive feature, response to request, response to robot request or vice versa false attempt, close, total failure, failure to respond after responding respectfully to request, respond with reputation risks, clear definables or bona fide glossary, login attempts, aggregates, opt out, opt less in, blindness radar, actual response to actual request, timidability versus publishability, royalty if any, etc.