Add Builder argument to IAIClientFactory methods

[MikeAlhayek]

This pull request introduces new overloads to the IAIClientFactory interface that allow callers to configure the builder pipeline for AI clients (chat, embeddings, image generation, speech-to-text, and text-to-speech) before the factory builds the final client. This enables middleware such as UseDefaultResilience() to be applied during client creation, making it easier to add resilience and other behaviors. The documentation and changelogs have been updated to reflect these new patterns, providing clear examples for both the new and existing approaches.

API Enhancements:

• Added overloads to IAIClientFactory for all major AI client types (IChatClient, IEmbeddingGenerator, IImageGenerator, ISpeechToTextClient, ITextToSpeechClient) that accept a builder-configuration delegate, allowing middleware (like resilience policies) to be applied before building the client. [1] [2] [3] [4] [5]

Documentation Updates:

• Updated documentation in ai-core.md, ai-resilience.md, and getting-started-aspnet.md to show how to use the new IAIClientFactory overloads for configuring resilience and other middleware, including code examples and guidance on when to use each approach. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

Changelog and Package References:

• Added a changelog entry describing the new overloads and their use cases.
• Added a package reference to Microsoft.Extensions.AI in the project file to support the new builder extensions.

These changes make it easier and more consistent to apply cross-cutting concerns like resilience to AI clients, whether you are using the factory or building clients manually.