chore: add devcontainer

.devcontainer/Dockerfile

@@ -0,0 +1,7 @@
+# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.163.1/containers/javascript-node/.devcontainer/base.Dockerfile
+
+ARG VARIANT="14-buster"
+FROM mcr.microsoft.com/vscode/devcontainers/javascript-node:0-${VARIANT}
+
+ARG EXTRA_NODE_VERSION=16
+RUN su node -c "source /usr/local/share/nvm/nvm.sh && nvm install ${EXTRA_NODE_VERSION}"