c988119386
This change adds additional Tonic templates for automatically generating bindings for Dart FFI, as well as serialisation of the bindings. - Adds parallel FfiDispather templates to the existing DartDispatcher used for (old) native bindings. - Adds serialisation of the bindings to enable automatic conversion and verification. - Extends existing DartConverters with conversions to and from the FFI transport types. - Adds new test (ffi_native_unittest.cc) for the above. This will allow us to replace the existing native functions in e.g. dart:ui with new Dart FFI native functions.