Merged PR 780180: Use ADO library for GitHub secrets

- Moves the github deploykey out of the keyvault into a pipeline variable group

Related work items: #2169865

.azdo/rolling/jobs/publish.yml

@@ -151,14 +151,8 @@ jobs:
   - checkout: self
     fetchTags: true
   
-  - task: DownloadSecureFile@1
-    name: File_Known_Hosts
-    displayName: Download secure file
-    inputs:
-      secureFile: buildxl_github_known_hosts
-  
   - task: PowerShell@2
     displayName: Force push to GitHub master SSH
     inputs:
       filePath: Shared/Scripts/github/PushToGHWithDeployKey.ps1
-      arguments: '"$(Key-Github-DeployKey-PrivateKey)" "$(Key-Github-DeployKey-PublicKey)" "$(File_Known_Hosts.secureFilePath)"'
+      arguments: '"$(Github-DeployKey-PrivateKey)" "$(Github-DeployKey-PublicKey)" "$(Build.SourcesDirectory)\Shared\Scripts\github\known_hosts"'

.azdo/rolling/pipeline.yml

@@ -94,7 +94,7 @@ extends:
     - stage: publish
       displayName: Publish
       variables:
-      - group: "BuildXL Secrets"
+      - group: "BuildXL GitHub Secrets"
       dependsOn: [CB, RCIT, External, Linux, Mac]
       condition: and(succeeded(), eq(variables.isPublishingBranch, true))
       jobs:

Shared/Scripts/github/known_hosts

@@ -0,0 +1,3 @@
+github.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOMqqnkVzrm0SdG6UOoqKLsabgH5C9okWi0dh2l9GKJl
+github.com ssh-rsa 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
+github.com ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBEmKSENjQEezOmxkZMy7opKgwFB9nkt5YRrYMjNuG5N87uRgg6CLrbo5wAdT/y6v0mKV0U2w0WZ2YB/++Tpockg=