Rust Object API (#6070)

* inital commit of rust object api

* Required fields support.

* clang fallthrough

* Fix unused variables

* just don't fall through

* remove comment

* s/panic/unreachable

* Tests for object API

* Added defaults

* deleted unintentionally added files and updated .bat file

* fix bat file

* clang format

* Cargo clippy checks

* remove commented out code

* clippy allows

* Remove matches! macro since we're not yet at Rust v1.42

* install clippy in RustTest.sh

* move line

Co-authored-by: Casper Neo <cneo@google.com>

samples/sample_binary.rs

@@ -19,6 +19,7 @@ extern crate flatbuffers;
 
 // import the generated code
 #[path = "./monster_generated.rs"]
+#[allow(clippy::approx_constant)]  // We use low precision PI as a default value.
 mod monster_generated;
 pub use monster_generated::my_game::sample::{Color, Equipment,
                                              Monster, MonsterArgs,
@@ -27,7 +28,7 @@ pub use monster_generated::my_game::sample::{Color, Equipment,
 
 
 // Example how to use FlatBuffers to create and read binary buffers.
-
+#[allow(clippy::float_cmp)]
 fn main() {
   // Build up a serialized buffer algorithmically.
   // Initialize it with a capacity of 1024 bytes.