* Update state processing for v0.12
* Fix EF test runners for v0.12
* Fix some tests
* Fix broken attestation verification test
* More test fixes
* Fix typo found in review
* Move the codes that loads Eth2Config from config to environment
* Move the codes that setups Eth2Config for testnet
* Move the codes that creates a new ChainSpec
* Remove unused `mut`
* Reduce local variable number
* Remove unused outputs of config::get_configs()
* Change the method name from plural to singular
* DRY the const `ETH2_CONFIG_FILENAME`
* Add comments
* Remove unnecessary blank line
* cargo fmt
* Add tests for EnvironmentBuilder::setup_eth2_config()
* Remove the comment that have been fixed
* Reduce local variable
* Remove redundant local variable
* Remove prysm-specific codes
Now the spec is in the eth2-testnets repo
