feature : mock server

[Bughue]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

提供mock-server能力，允许客户端进行通信方面的测试，同时为多版本协议的完整测试提供基础。
目前所有接口都默认返回成功，打算这几天用http接口控制模式，模拟普通提交、普通回滚、一阶段超时等等场景。大家有更好的建议也可以提出
Provides mock-server capability to allow client-side testing of communication aspects while providing a basis for complete testing of multiple versions of protocols.
Currently all interfaces return success by default, and intend to use the http interface control mode in the next few days to simulate scenarios such as normal commits, normal rollbacks, one-phase timeouts, and so on.
You can also suggest better suggestions

Ⅱ. Does this pull request fix one issue?

fixes #6212

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1a57f2d) 49.03% compared to head (818c1db) 49.81%.
Report is 20 commits behind head on 2.x.

❗ Current head 818c1db differs from pull request most recent head ea1d9c4. Consider uploading reports for the commit ea1d9c4 to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #6205      +/-   ##
============================================
+ Coverage     49.03%   49.81%   +0.78%     
- Complexity     4786     4931     +145     
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  Files           915      917       +2     
  Lines         31896    32010     +114     
  Branches       3855     3862       +7     
============================================
+ Hits          15641    15947     +306     
+ Misses        14699    14505     -194     
- Partials       1556     1558       +2     

see 63 files with indirect coverage changes

[xingfudeshi]

Please add change log

[slievrly]

Pls add mock-server's test set to the test module.

[xingfudeshi]

LGTM

[Bughue]

Pls add mock-server's test set to the test module.

done