fix(hz): fix some problems with hz client code

[Skyenought]

What type of PR is this?

fix

Check the PR title.

• [x] This PR title match the format: \<type>(optional scope): \<description>
• [x] The description of this PR title is user-oriented and clear enough for others to understand.
• [x] Attach the PR updating the user documentation if the current PR requires user awareness at the usage level. User docs repo

(Optional) Translate the PR title into Chinese.

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

en:

1. Assert all 'api.any' to 'api.post' when generate client code
2. Add addHeaders() method to prevent the generated code from failing to compile

zh(optional):

1. 在hz client 生成文件时, 将 api.any 全部转换为 api.post 注解
2. 增加 addHeaders() 方法，防止生成代码无法通过编译

(Optional) Which issue(s) this PR fixes:

(Optional) The PR that updates user documentation:

https://github.com/cloudwego/cloudwego.github.io/pull/939

[Skyenought]

genClient 不是只有在 client 命令下才执行的嘛😂

[Skyenought]

@FGYFFFF

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (0d25abe) 82.49% compared to head (171b252) 82.54%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #1053 +/- ## =========================================== + Coverage 82.49% 82.54% +0.04% =========================================== Files 98 98 Lines 10025 10025 =========================================== + Hits 8270 8275 +5 + Misses 1258 1254 -4 + Partials 497 496 -1 ```

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[Skyenought]

不好意思, 手快了