feat: 添加wav2vec和wav2vec2完整中文注释

[yqqxybm]

• 为wav2vec.py添加逐行中文注释，包含所有类和方法的详细说明
• 为wav2vec2.py添加完整中文注释，覆盖154个配置参数和所有核心组件
• 注释涵盖算法原理、设计决策、工程优化等技术细节
• 提供维度变化、数据流程、掩码策略等深度解析
• 增强代码可读性和教学价值，适合深度学习和语音处理学习

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• Did you write any new necessary tests?

What does this PR do?

Fixes # (issue).

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