Most notable changes are the updates to the test contracts: due to https://eips.ethereum.org/EIPS/eip-6780, SELFDESTRUCT no longer destroys a contract (unless it occurs in the creating transaction), so CREATE2 can no longer redeploy contracts to the same address.
Reviewed-on: #264
Now uses:
* ipld direct_by_leaf StateDB for basic queries
* trie_by_cid StateDB for trie slice and proof queries
Also:
* vulcanize => cerc refactor
* Backend method to close dbs
* state tests are in multiple packages, to allow separate ginkgo suites
* removes gap-filler module
* integration tests and github workflows
* run stack-orchestrator for testnet
* fix various issues with tests, hardhat server, dockerfile
* fix cmd flags / env vars
* fix flaky tests and clean up code
* remove unused code, scripts
* remove outdated docs
* update version
