chore: Refactor struct message generation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 75.43860% with 14 lines in your changes missing coverage. Please review.

Project coverage is 82.24%. Comparing base (4c5a678) to head (3263d69).

Files	Patch %	Lines
...ia-derive/src/contract/communication/struct_msg.rs	76.59%	11 Missing :warning:
sylvia-derive/src/parser/mod.rs	57.14%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #412 +/- ## ========================================== - Coverage 82.30% 82.24% -0.06% ========================================== Files 53 53 Lines 3113 3098 -15 ========================================== - Hits 2562 2548 -14 + Misses 551 550 -1 ```

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