Add agent, agentic workflow for architectural review against guidelines

[heaths]

Create a custom agent with distilled tokens from guidelines to aide in architectural (API) reviews. This can be invoked manually, or from an agentic workflow 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

[heaths]

We can link to the guidelines as well, but there's a lot of "fluff" we could probably distill to reduce tokens. It'd be great if we could actually fine tune an existing model so we don't have to send it tokens every time. Something to look into.