fix: code_gen client stream should import WithDoFinish

[felix021]

What type of PR is this?

fix

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fix: 生成代码里的 Client Stream 应当实现 WithDoFinish 接口

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en: The client stream in codegen is another Stream wrapper, which leads to failure when performing type assertion in streaming.FinishStream(st, err)
zh(optional): 生成代码里的 Client Stream 对 Stream 多做了一层封装，因此在 streaming.FinishStream(st, err) 里做 type assertion 会失败。

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.49%. Comparing base (b4906e4) to head (e2fe9fb).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1280      +/-   ##
===========================================
- Coverage    68.53%   68.49%   -0.04%     
===========================================
  Files          285      285              
  Lines        20643    20643              
===========================================
- Hits         14147    14140       -7     
- Misses        5315     5322       +7     
  Partials      1181     1181              

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