v2.4.0

• Please refer to https://fzyzcjy.github.io/flutter_rust_bridge/guides/miscellaneous/whats-new for what's changed in V2.
• Adds dart fix when generating files #2182 (thanks @AlexV525)
• Fix segfault when passing DartOpaque through ffi boundaries #2259 (thanks @alexlapa)
• Use generated in files to follow rustfmt #2263 (thanks @atezet)
• Fix dart fix command line arg #2288
• Allow pubspec.lock be missing #2289
• Support Clone+Debug+Default for RustAutoOpaque #2293
• Allow RustAutoOpaque inner value to be non-Clone #2293
• Fix struct field does not handle custom serializers #2294
• Remove importing dart:js_util and generalize SSE codec type handling #2295