* Adding the explorer API
* Added explorer-api to workspace
* Re-jigged explorer api cargo paths
* Fixed compiler warnings
* Removing unused code
* network-explorer-api: configure state with env var API_STATE_FILE or fall back to default value of `explorer-api-state.json`
* network-explorer-api: updates to `Cargo.lock` file after rebasing
* network-explorer-api: make clippy happy