Add agent, agentic workflow for architectural review against guidelines

Create a [custom agent](https://copilot-academy.github.io/workshops/copilot-customization/custom_agent_developer_guide) with distilled tokens from [guidelines](https://azure.github.io/azure-sdk/rust_introduction.html) to aide in architectural (API) reviews. This can be invoked manually, or from an [agentic workflow](https://copilot-academy.github.io/workshops/copilot-customization/agentic_workflows) based on some trigger - perhaps a label as @xirzec pointed out in the JS repo at https://github.com/Azure/azure-sdk-for-js/blob/main/.github/workflows/archie.md