Enable authenticated search from Kiota

[darrelmiller]

This will allow us to allow finding APIs advertised via the Topic in private GitHub repos.

Option 1:

Using the GitHub CLI to login to GitHub and then transparently allow Kiota to reuse that sign in context.
This will not work for Kiota web. We would need to provide a login redirect to GitHub.

Option 2

Add explicit sign-in to Kiota CLI

kiota login github  // This enables searching through private/internal GitHub repos for OpenAPI descriptions.