[Rust] Add support for fixed size arrays (#6548)

* Add support for fixed size arrays

* clang-format

* Update rust image to 1.51 to support const generics

* Handle correctly big endian

* Add fuzz tests and clean code

* Add struct fuzz test and optimize struct arrays for api

* Bump flatbuffers crate version

tests/docker/languages/Dockerfile.testing.rust.big_endian.1_51_0

@@ -0,0 +1,15 @@
+FROM rust:1.51.0-slim as base
+RUN apt -qq update -y && apt -qq install -y \
+    gcc-mips-linux-gnu \
+    libexpat1 \
+    libmagic1 \
+    libmpdec2 \
+    libreadline7 \
+    qemu-user
+RUN rustup target add mips-unknown-linux-gnu
+WORKDIR /code
+ADD . .
+RUN cp flatc_debian_stretch flatc
+WORKDIR /code/tests
+RUN rustc --version
+RUN ./RustTest.sh mips-unknown-linux-gnu