sloproxy

chore(plugin/jshandler): remove JS handler plugin implementation and related tests master

- Removed the entire `jshandler` plugin implementation, including `abi.go`, `engine.go`, `config.go`, and associated test files. - Deleted the `scripts` directory containing JavaScript examples. - Cleaned up the `go.mod` and `go.sum` dependencies related to `jshandler`. - Ensured redundant code and files associated with the removed plugin are purged from the repository.