Improve reliability of binding generation

[JssDWt]

The binding generation currently depends on a number of factors, including the operating system you're on. Like the kotlin formatter for react native behaves differently on macos-12 and macos-13.

Suggestion:
Create a nix environment to generate the flutter and react native bindings in. This would make binding generation reproducible between platforms.

[ok300]

The trouble seems to be that on macos-latest homebrew installs either 1.0.1 or 1.1.1 of ktlint:

https://github.com/breez/breez-sdk/blob/c60b12264e7f9103283c8fa4c57e2c3423faaeec/.github/workflows/main.yml#L206

This doesn't happen on macos-13. I think its because of caching or homebrew local mirrors that GH might be experimenting with.

I agree a nix way would be better.

[ok300]

Related: breez/breez-sdk-docs#128