feat: add support for secure encrypted access to Aliyun models

[karsonto]

This PR implements secure encrypted access to Aliyun DashScope models using AES-GCM encryption with RSA key exchange, addressing issue #497. The implementation follows Aliyun's encryption protocol requirements for secure cloud model inference, supporting TLS encryption and token-based authentication to comply with enterprise security policies.

With Encryption (New Feature):
DashScopeChatModel model = DashScopeChatModel.builder()
.apiKey(System.getenv("DASHSCOPE_API_KEY"))
.modelName("qwen-max")
.enableEncrypt(true) // Automatically fetches public key from API
.build();

[cla-assistant]

All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 84.97653% with 32 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../io/agentscope/core/model/DashScopeHttpClient.java	84.16%	15 Missing and 4 partials ⚠️
...ore/formatter/dashscope/dto/DashScopeResponse.java	53.84%	3 Missing and 3 partials ⚠️
...gentscope/core/model/DashScopeEncryptionUtils.java	91.11%	4 Missing ⚠️
...tter/dashscope/dto/DashScopePublicKeyResponse.java	90.47%	1 Missing and 1 partial ⚠️
...a/io/agentscope/core/model/DashScopeChatModel.java	92.85%	0 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

[AlbumenJ]

Can we implement https://help.aliyun.com/zh/model-studio/model-interface-aes-encryption in DashScopeChatModel?

[karsonto]

@AlbumenJ Could you please review this?