* fix for rust build
* Rust: Implement Serialize on generated types
For debugging convenience it is really handy to be able to dump out
types as another format (ie: json). For example, if we are logging a
type to a structured logging system, or even printing it out in a
structured way to the console.
Right now we handle this by shelling out to `flatc` which is not ideal;
by implementing Serialize on the generated types we can use any of the
Serializer-implementing packages for our structured debug output.
* clang-format
* Make the flatbuffers Rust crate only have an optional dependency on the `serde` packages.
* fix warning
* fix rust test build
* Oh yeah this needs to be initialized
* fix toml syntax
* code review feedback
* rebuild test data
