Implement refresh token support for Google API access

[haacked]

Related to #48

Implements automatic refresh token handling for Google authentication to maintain access to the Google People API without requiring a logout and login.

• Authentication Updates: Modifies src/OpenAIDemo.Web/Startup/ServiceExtensions.cs to request a refresh token during Google authentication and stores the refresh token in the user's database record if available.
• Google API Client Enhancements: Updates src/OpenAIDemo.Web/Library/GoogleApiClient.cs with a method to refresh the access token using the stored refresh token and adjusts existing methods to utilize the refreshed token if the current token is expired.
• Configuration Adjustments: Adds a property to src/OpenAIDemo.Web/Startup/Config/GoogleOptions.cs for storing the Google OAuth refresh token endpoint URL.
• Database Schema Extension: Introduces a new property in src/OpenAIDemo.Web/Entities/User.cs to store the refresh token for each user.

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[haacked]

I’m going to try a different approach