Add check to ensure Rust and Dart has in-sync generated code

[fzyzcjy]

Changes

Related: #1863

Checklist

• [ ] An issue to be fixed by this PR is listed above.
• [ ] New tests are added to ensure new features are working. Please refer to this page to see how to add a test.
• [ ] ./frb_internal precommit --mode slow (or fast) is run (it internal runs code generator, does auto formatting, etc).
• [ ] If this PR adds/changes features, documentations (in the ./website folder) are updated.
• [ ] CI is passing. Please refer to this page to see how to solve a failed CI.

Remark for PR creator

• ./frb_internal --help shows utilities for development.
• If fzyzcjy does not reply for a few days, maybe he just did not see it, so please ping him.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.59259% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 97.79%. Comparing base (d6fc16d) to head (0a4cc30).

:exclamation: Current head 0a4cc30 differs from pull request most recent head c88aec9. Consider uploading reports for the commit c88aec9 to get more accurate results

Files	Patch %	Lines
frb_dart/lib/src/main_components/entrypoint.dart	63.63%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1878 +/- ## ========================================== - Coverage 99.27% 97.79% -1.49% ========================================== Files 365 365 Lines 15484 15497 +13 ========================================== - Hits 15372 15155 -217 - Misses 112 342 +230 ```

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