* Refactors to replace most of the code with the statediff plugin.
* Adds basic CI test workflows for Gitea
* Refactors fixtures to use https://git.vdb.to/cerc-io/eth-testing
* Renames env vars for consistency with flags and other services:
- LOGRUS_{LEVEL,FILE} => LOG_LEVEL, etc.
- LVL_DB_PATH => LEVELDB_PATH
- ANCIENT_DB_PATH => LEVELDB_ANCIENT
- These will need to be updated wherever they are used
Reviewed-on: #1
