Setup pipeline to sync common engineering directory

eng/common/README.md

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+# Common Engineering System
+
+The `eng/common` directory contains engineering files that are common across the various azure-sdk language repos.
+It should remain relatively small and only contain textual based files like scripts, configs, or templates. It
+should not contain binary files as they don't play well with git.
+
+# Updating
+
+Any updates to files in the `eng/common` directory should be made in the [azure-sdk-tools](https://github.com/azure/azure-sdk-tools) repo.
+All changes made will cause a PR to created in all subscribed azure-sdk language repos which will blindly replace all contents of
+the `eng/common` directory in that repo. For that reason do **NOT** make changes to files in this directory in the individual azure-sdk
+languages repos as they will be overwritten the next time an update is taken from the common azure-sdk-tools repo.

eng/pipelines/eng-common-sync.yml

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+# Mirror the eng/common folder to all subscribed langauge repos.
+
+trigger:
+  branches:
+    include:
+      - master
+  paths:
+    include:
+      - eng/common
+
+pr: none
+
+resources:
+  repositories:
+    - repository: azure-sdk-build-tools
+      type: git
+      name: internal/azure-sdk-build-tools
+
+pool:
+  vmImage: ubuntu-18.04
+
+jobs:
+  - job: SyncEngCommon
+    displayName: Sync eng/common Directory
+
+    steps:
+    - template: tools/clone-buildtools/clone-buildtools.yml@azure-sdk-build-tools
+    - template: ./templates/steps/sync-directory.yml
+      parameters:
+        CommitMessage: Sync eng/common directory with azure-sdk-tools repository
+        DirectoryToSync: eng/common
+        Repos:
+          - azure-sdk-for-android
+          - azure-sdk-for-c
+          - azure-sdk-for-go
+          - azure-sdk-for-ios
+          - azure-sdk-for-java
+          - azure-sdk-for-js
+          - azure-sdk-for-net
+          - azure-sdk-for-python

eng/pipelines/templates/steps/sync-directory.yml

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+parameters:
+  Repos: []
+  DirectoryToSync: eng/common
+  CommitMessage: commit-message-not-set
+
+steps:
+
+- ${{ each repo in parameters.Repos }}:
+  - pwsh: |
+      git clone --branch master https://github.com/azure/${{ repo }}
+      $repoPath = "${{ repo }}/${{ parameters.DirectoryToSync }}"
+
+      if (!(Test-Path $repoPath)) { mkdir $repoPath }
+      rm -v -r $repoPath/*.*
+      cp -v -r $(Build.SourcesDirectory)/${{ parameters.DirectoryToSync }}/*.* $repoPath
+      ls -r $repoPath
+
+    displayName: Copy ${{ parameters.DirectoryToSync }} from azure-sdk-tools to ${{ repo }}
+
+  - template: pipelines/steps/create-pull-request.yml@azure-sdk-build-tools
+    parameters:
+      RepoName: ${{ repo }}
+      PRBranchName: sync-${{ parameters.DirectoryToSync }}
+      CommitMsg: ${{ parameters.CommitMessage }}
+      PushArgs: -f
+      WorkingDirectory: $(System.DefaultWorkingDirectory)/${{ repo }}