feat: add devcontainers for enabling github codespaces usage.

.devcontainer/Dockerfile

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+# Reference - https://github.com/microsoft/vscode-dev-containers/tree/main/containers/java-8/.devcontainer
+# [Choice] Debian OS version (use bullseye on local arm64/Apple Silicon): buster, bullseye
+# [Choice] Java version (use -bullseye variants on local arm64/Apple Silicon): 11, 17, 11-bullseye, 17-bullseye, 11-buster, 17-buster
+ARG VARIANT="bullseye"
+FROM mcr.microsoft.com/vscode/devcontainers/java:11-${VARIANT}
+
+# [Option] Install Maven
+ARG INSTALL_MAVEN="true"
+ARG MAVEN_VERSION=""
+# [Option] Install Gradle
+ARG INSTALL_GRADLE="false"
+ARG GRADLE_VERSION=""
+RUN if [ "${INSTALL_MAVEN}" = "true" ]; then su vscode -c "umask 0002 && . /usr/local/sdkman/bin/sdkman-init.sh && sdk install maven \"${MAVEN_VERSION}\""; fi \
+    && if [ "${INSTALL_GRADLE}" = "true" ]; then su vscode -c "umask 0002 && . /usr/local/sdkman/bin/sdkman-init.sh && sdk install gradle \"${GRADLE_VERSION}\""; fi
+
+# [Choice] Node.js version: none, lts/*, 16, 14, 12, 10
+ARG NODE_VERSION="lts/*"
+RUN if [ "${NODE_VERSION}" != "none" ]; then su vscode -c "umask 0002 && . /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSION} 2>&1"; fi
+
+# install gloud sdk
+RUN echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] http://packages.cloud.google.com/apt cloud-sdk main" | tee -a /etc/apt/sources.list.d/google-cloud-sdk.list && curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key --keyring /usr/share/keyrings/cloud.google.gpg  add - && apt-get update -y && apt-get install google-cloud-cli -y

.devcontainer/devcontainer.json

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+{
+  "name": "Java 11",
+  "build": {
+    "dockerfile": "Dockerfile",
+    "args": {
+      // Use the VARIANT arg to pick a Debian OS version: buster, bullseye
+      // Use bullseye when running on local arm64/Apple Silicon.
+      "VARIANT": "bullseye",
+      // Options
+      "INSTALL_MAVEN": "true",
+      "INSTALL_GRADLE": "false",
+      "NODE_VERSION": "lts/*"
+    }
+  },
+
+  // Configure tool-specific properties.
+  "customizations": {
+    // Configure properties specific to VS Code.
+    "vscode": {
+      // Set *default* container specific settings.json values on container create.
+      "settings": {
+        "java.import.gradle.java.home": "/usr/local/sdkman/candidates/java/current",
+        "java.configuration.runtimes": [{
+          "default": true,
+          "name": "JavaSE-11",
+          "path": "/usr/local/sdkman/candidates/java/current"
+        }]
+      },
+
+      // Add the IDs of extensions you want installed when the container is created.
+      "extensions": [
+        "vscjava.vscode-java-pack",
+        "ms-azuretools.vscode-docker"
+      ]
+    }
+  },
+
+  // Use 'forwardPorts' to make a list of ports inside the container available locally.
+  // "forwardPorts": [],
+
+  // Use 'postCreateCommand' to run commands after the container is created.
+  "postCreateCommand": "bash .devcontainer/postCreate.sh",
+
+  // Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+  "remoteUser": "vscode"
+}

.devcontainer/postCreate.sh

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+echo "Post Create Starting"
+
+mvn install -B -V -ntp \
+    -DskipTests=true \
+    -Dmaven.javadoc.skip=true \
+    -Dclirr.skip=true