Add RunEvaluationOperator for Google Vertex AI Rapid Evaluation API

[CYarros10]

The Gen AI Evaluation Service lets you evaluate your large language models (LLMs), both pointwise and pairwise, across several metrics, with your own criteria. You can provide inference-time inputs, LLM responses and additional parameters, and the Gen AI Evaluation Service returns metrics specific to the evaluation task.

Metrics include model-based metrics, such as PointwiseMetric and PairwiseMetric, and in-memory computed metrics, such as rouge, bleu, and tool function-call metrics. PointwiseMetric and PairwiseMetric are generic model-based metrics that you can customize with your own criteria. Because the service takes the prediction results directly from models as input, the evaluation service can perform both inference and subsequent evaluation on all models supported by Vertex AI.

For more information on evaluating a model, see Generative AI evaluation service overview.

Can be used as part of a larger LLMops DAG:

Training Dataset Lands --> GCSObjectExistenceSensor --> SupervisedFineTuningTrainOperator --> RunEvaluationOperator --> CountTokensOperator --> GenerativeModelGenerateContentOperator

Note: Fixes/Replaces closed PR 41919

---

^ Add meaningful description above
Read the Pull Request Guidelines for more information.
In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in newsfragments.

[MaksYermak]

LGTM