Unify Hive test driver and spec-test runner

[MegaRedHand]

We currently have the logic duplicated in both places (rpc crate and blockchain/tests). We should unify them, or maybe start running hive in our CI, whichever's easiest.

[dicethedev]

You can assign me this

[MegaRedHand]

Sure. There's a PR already tackling this: #375, but the author doesn't seem to be responding, so feel free to continue it by looking at the review comments (you'll have to open a new PR though).

Edit: ignore this. I misread the issue title 🤦