Add support for codespaces

.devcontainer/Dockerfile

@@ -0,0 +1,15 @@
+FROM mcr.microsoft.com/vscode/devcontainers/base:debian-10
+
+ENV DENO_INSTALL=/deno
+RUN mkdir -p /deno \
+    && curl -fsSL https://deno.land/x/install/install.sh | sh \
+    && chown -R vscode /deno
+
+ENV PATH=${DENO_INSTALL}/bin:${PATH} \
+    DENO_DIR=${DENO_INSTALL}/.cache/deno
+
+RUN deno cache deps.ts
+
+# [Optional] Uncomment this section to install additional OS packages.
+# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+#    && apt-get -y install --no-install-recommends <your-package-list-here>