Add a new built-in (pre-built) LLM classification evaluator to the Phoenix evals libraries, and optionally promote it to a server-side dataset evaluator. Use when working in the Phoenix repo and asked to add a new built-in eval, pre-built metric, builtin evaluator, or LLM-as-a-judge template that ships with arize-phoenix-evals / @arizeai/phoenix-evals, or to promote an existing one to the dataset evaluators UI. Do not use for writing a user's own custom evaluator for their app (use phoenix-evals).