[s360-breeze-toolkit: SFI-ES4.2.4] ES 4.2.4 Network Isolation Policy Implementation

[v-sohmondal]

This pull request updates the build and package management configurations across multiple sample projects to improve security and compliance. The main changes enforce the use of an internal package-feed proxy (Central Feed Services) for all package restores and add network isolation policies to pipeline configurations to block unintended public package-feed calls.

Pipeline configuration improvements:

• Added the networkIsolationPolicy: Permissive,CFSClean setting to the azure-pipelines.yml files for all sample projects, which helps block involuntary public package-feed calls during builds. [1] [2] [3]

Package restore routing:

• Added or updated .npmrc files in the TypeScript sample projects to route npm package restores through the internal package-feed proxy at https://packagefeedproxy.microsoft.io/npm/.
• Added a nuget.config file to the C# sample project to route NuGet package restores through the internal package-feed proxy at https://packagefeedproxy.microsoft.io/nuget/v3/index.json.