Use portable-atomic in frb_rust

[kyrias]

Not all targets supports AtomicU64 which currently makes it difficult to share the same crate between multiple targets. portable-atomic uses the std version of the type if one exists and otherwise emulates a fallback using atomic CAS operations.

Changes

Please list issues fixed by this PR here, using format "Fixes #the-issue-number".

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.

[welcome[bot]]

Hi! Thanks for opening this pull request! :smile:

[kyrias]

I'm so confused here. I push something and some CI jobs fail. I run those locally and commit and push the pubspec.lock changes it complained about which then causes another CI job to fail because it wants the pubspec.lock file to be unchanged?

[fzyzcjy]

CI uses a fixed version of Flutter https://github.com/fzyzcjy/flutter_rust_bridge/blob/4f5cf68f56ed56df62264227d81891744c356403/.github/workflows/ci.yaml#L14. Thus, an easy way is to fix your local Flutter to 3.22.0 and run everything. Another way is to bump everything in CI (but not sure whether this will cause a merge conflict with something similar in https://github.com/fzyzcjy/flutter_rust_bridge/pull/2320#issuecomment-2378343810)

[fzyzcjy]

@all-contributors please add @kyrias for code

[allcontributors[bot]]

@fzyzcjy

I've put up a pull request to add @kyrias! :tada:

[welcome[bot]]

Hi! Congrats on merging your first pull request! :tada: