Add pipeline for building PCL's environment docker image

.ci/azure-pipelines/env.yml

@@ -0,0 +1,84 @@
+# Docker
+# Build a Docker image 
+# https://docs.microsoft.com/azure/devops/pipelines/languages/docker
+
+trigger:
+  branches:
+    include:
+    - master
+  paths:
+    include:
+    - .dev/docker/env/Dockerfile
+
+pr:
+  branches:
+    include:
+    - master
+  paths:
+    include:
+    - .dev/docker/env/Dockerfile
+
+schedules:
+- cron: "0 0 0 * *"
+  displayName: "Sunday midnight build"
+  branches:
+    include:
+    - master
+
+resources:
+- repo: self
+
+variables:
+  dockerHub: "PersonalDockerHub"
+  dockerHubID: "PointCloudLibrary"
+
+stages:
+- stage: BuildAndPush
+  displayName: "Build env"
+  jobs:
+  - job: BuildAndPush
+    timeoutInMinutes: 360
+    displayName: "env docker image: "
+    pool:
+      vmImage: 'ubuntu-latest'
+    strategy:
+      matrix:
+        Ubuntu 16.04:
+          CUDA_VERSION: 9.2
+          UBUNTU_DISTRO: 16.04
+          USE_CUDA: true
+          VTK_VERSION: 6
+          tag: 16.04
+        Ubuntu 18.04:
+          CUDA_VERSION: 10.2
+          UBUNTU_DISTRO: 18.04
+          USE_CUDA: true
+          VTK_VERSION: 6
+          tag: 18.04
+        Ubuntu 20.04:
+          CUDA_VERSION: 11
+          UBUNTU_DISTRO: 20.04
+          VTK_VERSION: 7
+          USE_CUDA: ""
+          tag: 20.04
+    steps:
+    - task: Docker@2
+      displayName: "Build docker image: env:$(tag)"
+      inputs:
+        command: build
+        arguments: |
+          --no-cache
+          --build-arg UBUNTU_DISTRO=$(UBUNTU_DISTRO)
+          --build-arg VTK_VERSION=$(VTK_VERSION)
+          --build-arg USE_CUDA=true
+          -t $(dockerHubID)/env:$(tag)
+        dockerfile: '$(Build.SourcesDirectory)/.dev/docker/env/Dockerfile'
+        tags: "$(tag)"
+    - task: Docker@2
+      displayName: "Push docker image env:$(tag)"
+      inputs:
+        command: push
+        containerRegistry: $(dockerHub)
+        repository: $(dockerHubID)/env
+        tags: "$(tag)"
+        condition: eq(variables['Build.SourceBranch'], 'refs/heads/master')