What type of PR is this?

/kind feature

What does this PR do / why do we need it:
本 PR 添加了哈希防御方法以保护纵向联邦学习模型的隐私性，并提高系统的安全性和可靠性：
HashVFL in paper: ‘HashVFL: Defending Against Data Reconstruction Attacks in Vertical Federated Learning’.
同时添加了采用类似结构的舍入层方法来有效节省计算和提高性能：
RoundVFL in paper: 'Integer is Enough: When Vertical Federated Learning Meets Rounding'
Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewers:
请注意这个 PR 添加了新的哈希防御层和舍入层，确保梯度传递的准确性和避免梯度消失问题。详细的实现说明可以在 README.md 中找到。