feat: GenAI SDK client - Enabling Few-shot Prompt Optimization by passing either "OPTIMIZATION_TARGET_FEW_SHOT_RUBRICS" or "OPTIMIZATION_TARGET_FEW_SHOT_TARGET_RESPONSE" to the optimize_prompt method

feat: GenAI SDK client - Enabling Few-shot Prompt Optimization by passing either "OPTIMIZATION_TARGET_FEW_SHOT_RUBRICS" or "OPTIMIZATION_TARGET_FEW_SHOT_TARGET_RESPONSE" to the optimize_prompt method #1678