build: add devcontainer for codespaces

.devcontainer/Dockerfile

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+# [Choice] Debian OS version: bullseye, buster
+ARG VARIANT=bullseye
+FROM --platform=linux/amd64 mcr.microsoft.com/devcontainers/base:0-${VARIANT}
+
+ENV DENO_INSTALL=/deno
+RUN mkdir -p /deno \
+    && curl -fsSL https://deno.land/x/install/install.sh | sh \
+    && chown -R vscode /deno
+
+ENV PATH=${DENO_INSTALL}/bin:${PATH} \
+    DENO_DIR=${DENO_INSTALL}/.cache/deno
+
+# [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>

.devcontainer/devcontainer.json

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+{
+	"name": "Deno",
+ 	"build": {
+		"dockerfile": "Dockerfile"
+	},
+
+	// Configure tool-specific properties.
+	"customizations": {
+		// Configure properties specific to VS Code.
+		"vscode": {
+			// Set *default* container specific settings.json values on container create.
+			"settings": { 
+				// Enables the project as a Deno project
+				"deno.enable": true,
+				// Enables Deno linting for the project
+				"deno.lint": true,
+				// Sets Deno as the default formatter for the project
+				"editor.defaultFormatter": "denoland.vscode-deno"
+			},
+			
+			// Add the IDs of extensions you want installed when the container is created.
+			"extensions": [
+				"denoland.vscode-deno"
+			]
+		}
+	},
+
+	"remoteUser": "vscode"
+}