Automatically wait when concurrent mutable access, while still preventing deadlocks

[fzyzcjy]

Changes

Close https://github.com/fzyzcjy/flutter_rust_bridge/issues/1883 Close https://github.com/fzyzcjy/flutter_rust_bridge/issues/1914 Close https://github.com/fzyzcjy/flutter_rust_bridge/issues/1917

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 98.55072% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 99.24%. Comparing base (8915d06) to head (d584832).

Files	Patch %	Lines
frb_rust/src/rust_auto_opaque/inner.rs	81.81%	2 Missing :warning:
frb_rust/src/rust_auto_opaque/dart2rust.rs	99.02%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1920 +/- ## ========================================== - Coverage 99.25% 99.24% -0.02% ========================================== Files 365 368 +3 Lines 15533 15710 +177 ========================================== + Hits 15417 15591 +174 - Misses 116 119 +3 ```

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