Update create auth npmrc

[chidozieononiwu]

This pull request updates the create-authenticated-npmrc.yml pipeline template to improve how the .npmrc file path is handled and to enhance compatibility and robustness in pipeline jobs. The most important changes are grouped below:

Improvements to .npmrc Path Handling:

• The npmrcPath parameter now defaults to an empty string, which causes the script to use the agent user's default .npmrc location if not specified, ensuring all subsequent npm-related commands inherit the correct configuration.
• The script now dynamically sets and uses a resolved .npmrc path, storing it in a pipeline variable (resolvedNpmrcPath) for use in later steps, improving reliability and flexibility.

Code Quality and Consistency:

• Consistent use of double quotes for parameter defaults and improved formatting for readability.
• The script now checks for the existence of the parent folder before creating it, and only attempts to create it if necessary, reducing unnecessary operations.
• The .npmrc file is now created with only the registry line (removing always-auth=true), aligning with updated authentication practices.

[Copilot]

Pull request overview

Updates the shared Azure Pipelines step template for creating and authenticating an .npmrc, aiming to make .npmrc path handling more flexible and consistent across pipeline jobs.

Changes:

• Makes npmrcPath optional (defaults to empty) and resolves the effective path inside the PowerShell step.
• Stores the resolved path in a pipeline variable (resolvedNpmrcPath) and uses it for npmAuthenticate@0.
• Simplifies the generated .npmrc content to only include the registry= line.