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>

rust/flexbuffers/src/builder/mod.rs

@@ -242,9 +242,7 @@ impl<'a> Builder {
         let address = self.buffer.len();
         for &b in xs.iter() {
             self.buffer.push(b as u8);
-            for _ in 0..width as u8 {
-                self.buffer.push(0); // Well this seems wasteful.
-            }
+            self.buffer.resize(self.buffer.len() + width as usize, 0);
         }
         self.values.push(Value::Reference {
             fxb_type: FlexBufferType::VectorBool,