chore: refine the hg-style.xml specification

[msgui]

Purpose of the PR

subtask of https://github.com/apache/incubator-hugegraph/issues/2435

Main Changes

👉: https://github.com/apache/incubator-hugegraph/wiki/HugeGraph-Code-Style-Guide Add the option 'BLANK_LINES_AFTER_CLASS_HEADER' with a value of 1.

Verifying these changes

• [ ] Trivial rework / code cleanup without any test coverage. (No Need)
• [ ] Already covered by existing tests, such as (please modify tests here).
• [x] Need tests and can be verified as follows:
  • xxx

Does this PR potentially affect the following parts?

• [x] Nope
• [ ] Dependencies (add/update license info)
• [ ] Modify configurations
• [ ] The public API
• [ ] Other affects (typed here)

Documentation Status

• [ ] Doc - TODO
• [ ] Doc - Done
• [x] Doc - No Need

[codecov[bot]]

Codecov Report

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

Comparison is base (1d4532c) 66.23% compared to head (01f4ff0) 63.85%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2436 +/- ## ============================================ - Coverage 66.23% 63.85% -2.39% Complexity 828 828 ============================================ Files 511 511 Lines 42597 42597 Branches 5942 5942 ============================================ - Hits 28215 27200 -1015 - Misses 11566 12652 +1086 + Partials 2816 2745 -71 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.