Create blank starter templates for AI scenarios

Today we have the AI Chat Web App template (in preview) which demonstrates a prescriptive way to chat with custom data. In addition to this, we want to add blank starter templates that provide the minimal code needed to work with AI services, but without the extra data ingestion functionality.

Proposal:
* Change the AI Chat Web App template to include an option to "Include Sample Data", which is checked by default. When checked, the template works the same as it does today; when unchecked we exclude the data ingestion service code (and code that calls it), remove sample PDFs, and remove the citation support.
* Add an AI Chat Console App template that behaves the same as AI Chat Web App, but with a minimal console UI (maintain history, do not show citations, nor suggested follow-up questions).
* Add an AI Chat Web API template that uses Minimal API and provides a simple REST API that can be used for chat interactions (chat history is maintained by the client and passed in REST calls, no citations, no suggested follow-up questions).