Added npm auth step to internal feed (#48720)

* Added npm auth step to internal feed

* Added root nuget config to disable non-cfs feed

Author: raych1

NuGet.Config

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <clear />
+    <!-- Do not add any additional feeds. If new packages are needed they need to
+    come from the azure-sdk-for-net DevOps feed which has an upstream set to nuget.org -->
+    <add key="azure-sdk-for-net" value="https://pkgs.dev.azure.com/azure-sdk/public/_packaging/azure-sdk-for-net/nuget/v3/index.json" />
+  </packageSources>
+  <disabledPackageSources>
+    <clear />
+  </disabledPackageSources>
+</configuration>

eng/pipelines/templates/jobs/ci.yml

@@ -429,6 +429,11 @@ jobs:
           version: 22.x
         displayName: Use Node.js 22.x
 
+      # Authenticate npm to Azure Artifacts
+      - template: /eng/common/pipelines/templates/steps/create-authenticated-npmrc.yml
+        parameters:
+          npmrcPath: $(Agent.TempDirectory)/analyze-job/.npmrc
+
       - task: PowerShell@2
         displayName: Verify Swagger and TypeSpec Code Generation
         inputs:
@@ -437,6 +442,8 @@ jobs:
           arguments: >
             -ServiceDirectories '$(PRServiceDirectories)'
             -RegenerationType 'All'
+        env:
+          NPM_CONFIG_USERCONFIG: $(Agent.TempDirectory)/analyze-job/.npmrc
 
       # Authenticate with Azure Artifacts
       - template: /eng/pipelines/templates/steps/maven-authenticate.yml