feat(generative-ai): Add requirement files to feature folders

[msampathkumar]

Description

Add missing requirements.txt files to feature folders.

• Please merge this PR for me once it is approved

[snippet-bot]

You are about to delete the following sample browser pages.

• generative_ai/code_completion_test_function.py:18, tag aiplatform_sdk_code_completion_test_function(usage: page 1).
• generative_ai/code_generation_unittest.py:18, tag aiplatform_sdk_code_generation_unittest(usage: page 1).
• generative_ai/extraction.py:21, tag aiplatform_sdk_extraction(usage: page 1).
• generative_ai/sentiment_analysis.py:21, tag aiplatform_sdk_sentiment_analysis(usage: page 1).
• generative_ai/summarization.py:21, tag aiplatform_sdk_summarization(usage: page 1).

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Here is the summary of changes.

You are about to add 10 region tags.

• generative_ai/text_models/classify_news_items.py:18, tag generativeaionvertexai_classification
• generative_ai/text_models/code_completion_test_function.py:18, tag aiplatform_sdk_code_completion_test_function
• generative_ai/text_models/code_generation_unittest.py:18, tag aiplatform_sdk_code_generation_unittest
• generative_ai/text_models/extraction.py:21, tag aiplatform_sdk_extraction
• generative_ai/text_models/list_tuned_code_generation_models.py:21, tag aiplatform_sdk_list_tuned_code_generation_models
• generative_ai/text_models/sentiment_analysis.py:21, tag aiplatform_sdk_sentiment_analysis
• generative_ai/text_models/streaming_chat.py:21, tag aiplatform_streaming_chat
• generative_ai/text_models/streaming_code.py:21, tag aiplatform_streaming_code
• generative_ai/text_models/streaming_codechat.py:21, tag aiplatform_streaming_codechat
• generative_ai/text_models/summarization.py:21, tag aiplatform_sdk_summarization

You are about to delete 10 region tags.

• generative_ai/classify_news_items.py:18, tag generativeaionvertexai_classification
• generative_ai/code_completion_test_function.py:18, tag aiplatform_sdk_code_completion_test_function
• generative_ai/code_generation_unittest.py:18, tag aiplatform_sdk_code_generation_unittest
• generative_ai/extraction.py:21, tag aiplatform_sdk_extraction
• generative_ai/list_tuned_code_generation_models.py:21, tag aiplatform_sdk_list_tuned_code_generation_models
• generative_ai/sentiment_analysis.py:21, tag aiplatform_sdk_sentiment_analysis
• generative_ai/streaming_chat.py:21, tag aiplatform_streaming_chat
• generative_ai/streaming_code.py:21, tag aiplatform_streaming_code
• generative_ai/streaming_codechat.py:21, tag aiplatform_streaming_codechat
• generative_ai/summarization.py:21, tag aiplatform_sdk_summarization

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