Implement extcodehash

[ermalkaleci]

• Add manual tests for extcodehash because we can't hardcode the hash
• Update specs instantiate result to include code hash

TODO:

• [x] Update pallet-revive to return hardcoded hash for EOA

[xermicus]

Closes #63. @ermalkaleci if you feel like takling this on the runtime side too, can I assign #63 to you?

[ermalkaleci]

Absolutely, I would love to contribute. Hope this is good start :)

[xermicus]

Nice, thank you! Yeah we can take it from here. There's nothing complex to it, it is a good first issue.

[ermalkaleci]

@xermicus can you give this a review?