Add devcontainer support

.devcontainer/Dockerfile

+FROM storm2/ngx-voms-build
+
+USER root
+
+RUN yum install -y https://repo.ius.io/ius-release-el7.rpm centos-release-scl \
+    && yum install -y git224 devtoolset-10
+
+USER $BUILD_USER

.devcontainer/devcontainer.json

+// For format details, see https://aka.ms/vscode-remote/devcontainer.json or this file's README at:
+// https://github.com/microsoft/vscode-dev-containers/tree/v0.159.0/containers/cpp
+{
+  "name": "C++",
+  "build": {
+    "dockerfile": "Dockerfile",
+  },
+  "runArgs": [
+    "--cap-add=SYS_PTRACE",
+    "--security-opt",
+    "seccomp=unconfined"
+  ],
+  // Set *default* container specific settings.json values on container create.
+  "settings": {
+    "terminal.integrated.defaultProfile.linux": "bash"
+  },
+  // Add the IDs of extensions you want installed when the container is created.
+  "extensions": [
+    "ms-vscode.cpptools",
+  ],
+  // 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": "sudo debuginfo-install -y voms",
+  // Comment out this line to run as root instead.
+  "remoteUser": "build",
+  "remoteEnv": {"NGX_HTTP_VOMS_MODULE_ROOT": "${containerWorkspaceFolder}"}
+}
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