images: Add codegen image

Signed-off-by: Dave Tucker <dave@dtucker.co.uk>

images/Dockerfile.codegen

@@ -0,0 +1,25 @@
+FROM ubuntu:20.04
+
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+        build-essential \
+        clang \
+        ca-certificates \
+        curl \
+        git \
+        ssh \
+        libssl-dev \
+        pkg-config \
+        libc6-dev \
+        libc6-dev-arm64-cross \
+        libc6-dev-armel-cross \
+        libc6-dev-riscv64-cross \
+        && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+RUN echo "(curl https://sh.rustup.rs -sSf | sh -s -- -y --profile minimal -c rustfmt --default-toolchain nightly --no-modify-path) && rustup default nightly" > /install-rust.sh && chmod 755 /install-rust.sh
+RUN ./install-rust.sh