[feat] Addition of CD workflow

Part of Migration from CircleCI to GitHubActions

Ticket: https://mattermost.atlassian.net/browse/CLD-4811
Signed-off-by: Akis Maziotis <akis.maziotis@mattermost.com>

.github/workflows/cd.yml

@@ -0,0 +1,97 @@
+---
+name: cd
+on:
+  workflow_run:
+    workflows:
+      - ci
+    types:
+      - completed
+    branches-ignore:
+      - master
+      - release-**
+      - cloud-**
+defaults:
+  run:
+    shell: bash
+jobs:
+  prepare-docker-build:
+    runs-on: ubuntu-22.04
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    env:
+      REPO_NAME: ${{ github.event.repository.name }}
+    steps:
+    - name: ci/checkout-repo
+      uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
+    # We need to sanitize the branch name before using it
+    - name: ci/sanitize-branch-name
+      id: branch
+      uses: transferwise/sanitize-branch-name@b10b4d524ac5a7b645b43a3527db3a6cca017b9d # v1
+    # Search for the string "pull" and replace it with "PR" in branch-name
+    - name: ci/sanitize-branch-name-replace-pull-with-PR-
+      run: echo "BRANCH_NAME=$(echo ${{ steps.branch.outputs.sanitized-branch-name }} | sed 's/^pull\//PR-/g')" >> $GITHUB_ENV
+    - name: ci/artifacts-downloads
+      uses: actions/download-artifact@e9ef242655d12993efdcda9058dee2db83a2cb9b  # v3.0.2
+      with:
+        name: webapp-artifact
+    - name: ci/Download-server-bundle
+      run: |
+        curl -f -o server.tar.gz https://pr-builds.mattermost.com/mattermost-server/$BRANCH_NAME/mattermost-enterprise-linux-amd64.tar.gz || true
+        if [[ -f server.tar.gz ]]; then
+            echo "Downloaded server bundle for $BRANCH_NAME branch from pr-builds.mattermost.com"
+        else
+            curl -f -o server.tar.gz https://s3.amazonaws.com/releases.mattermost.com/gitlab/bundle/master/mattermost-enterprise-linux-amd64.tar.gz
+            echo "Downloaded server bundle for master from releases.mattermost.com"
+        fi
+        tar xf server.tar.gz
+    - name: ci/Replace-web-app
+      run: |
+        mv mattermost/client client-original
+        tar xf mattermost-webapp.tar.gz
+        mv client mattermost/client
+    - name: ci/Re-add-products
+      run: |
+        mv client-original/products mattermost/client/products
+    - name: ci/Repackage server bundle
+      run: |
+        tar -zcf mattermost-enterprise-linux-amd64.tar.gz mattermost/
+    - name: ci/persist-artifact
+      uses: actions/upload-artifact@0b7f8abb1508181956e8e162db84b466c27e18ce # v3.1.2
+      with:
+        name: mattermost-enterprise-linux-artifact
+        path: mattermost-enterprise-linux-amd64.tar.gz
+    - name: ci/aws-configure
+      uses: aws-actions/configure-aws-credentials@07c2f971bac433df982ccc261983ae443861db49 # v1-node16
+      with:
+        aws-region: ${{ secrets.AWS_REGION }}
+        aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
+        aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+    - name: ci/artifact-upload
+      run: |
+        aws s3 cp mattermost-enterprise-linux-amd64.tar.gz s3://${{secrets.AWS_S3_BUCKET_PRS}}/$REPO_NAME/commit/${{ github.sha }}/ --cache-control no-cache
+  build-docker:
+    runs-on: ubuntu-22.04
+    needs: prepare-docker-build
+    steps:
+    - name: cd/Set environment variables
+      id: vars
+      run: |
+        echo "TAG=`echo ${GITHUB_SHA} | cut -c1-8`" >> $GITHUB_ENV
+        echo "REPO_NAME=${{github.event.repository.name}}" >> $GITHUB_ENV
+    - name: cd/Login to Docker Hub
+      uses: docker/login-action@3da7dc6e2b31f99ef2cb9fb4c50fb0971e0d0139 # v2.1.0
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+    - name: cd/Setup Docker Buildx
+      uses: docker/setup-buildx-action@11e8a2e2910826a92412015c515187a2d6750279 # v2.4
+    - name: cd/docker-build-push
+      env:
+        DOCKER_CLI_EXPERIMENTAL: enabled
+      run: |
+        wget https://raw.githubusercontent.com/mattermost/mattermost-server/master/build/Dockerfile
+        wget https://raw.githubusercontent.com/mattermost/mattermost-server/master/build/entrypoint.sh
+        chmod +x entrypoint.sh
+        export MM_PACKAGE=https://pr-builds.mattermost.com/$REPO_NAME/commit/${{ github.sha }}/mattermost-enterprise-linux-amd64.tar.gz
+        docker buildx build --push --build-arg MM_PACKAGE=$MM_PACKAGE -t mattermost/mm-ee-test:${TAG} .
+
+