[CI] Add missing configuration stage for the macos tests pipeline.

tools/devops/automation/templates/mac/stage.yml

@@ -40,6 +40,49 @@ parameters:
   default: false
 
 stages:
+- stage: configure_build
+  displayName: '${{ parameters.stageDisplayNamePrefix }}Configure'
+  dependsOn: ${{ parameters.dependsOn }}
+  ${{ if and(ne(parameters.dependsOn, ''), ne(parameters.dependsOnResult, '')) }}:
+    condition: eq(dependencies.${{ parameters.dependsOn }}.result, '${{ parameters.dependsOnResult }}')
+  jobs:
+
+  - ${{ if eq(parameters.pool, 'automatic') }}:
+    - job: AgentPoolSelector       # https://docs.microsoft.com/en-us/azure/devops/pipelines/process/phases?view=azure-devops&tabs=yaml
+      pool:                        # Consider using an agentless (server) job here, but would need to host selection logic as an Azure function: https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema?view=azure-devops&tabs=schema#server
+        vmImage: ubuntu-latest
+      steps:
+      - checkout: none             # https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema?view=azure-devops&tabs=schema#checkout
+
+      # Selects appropriate agent pool based on trigger type (PR or CI); manually triggered builds target the PR pool
+      - template: azure-devops-pools/agent-pool-selector.yml@yaml-templates
+        parameters:
+          agentPoolPR: $(PRBuildPool)
+          agentPoolPRUrl: $(PRBuildPoolUrl)
+          agentPoolCI: $(CIBuildPool)
+          agentPoolCIUrl: $(CIBuildPoolUrl)
+
+  - job: configure
+    displayName: 'Configure build'
+    pool:
+      vmImage: windows-latest
+
+    variables:
+      isMain: $[eq(variables['Build.SourceBranch'], 'refs/heads/main')]
+      isScheduled: $[eq(variables['Build.Reason'], 'Schedule')]
+      BRANCH_NAME: $[ replace(variables['Build.SourceBranch'], 'refs/heads/', '') ]
+
+    steps:
+    - template: common/load_configuration.yml
+      parameters: 
+        repositoryAlias: ${{ parameters.repositoryAlias }}
+        commit: ${{ parameters.commit }}
+        testConfigurations: ${{ parameters.testConfigurations }}
+        supportedPlatforms: ${{ parameters.supportedPlatforms }}
+        testsLabels: '--label=skip-all-tests,run-ios-tests,run-ios-simulator-tests,run-tvos-tests,run-watchos-tests,run-mac-tests,run-maccatalyst-tests,run-dotnet-tests,run-system-permission-tests,run-legacy-xamarin-tests'
+        statusContext: 'VSTS: simulator tests' 
+        uploadArtifacts: true
+
 - stage: ${{ parameters.stageName }}
   displayName: ${{ parameters.displayName }}
   dependsOn: