chore: add environment variables to Bicep for local development setup

[Priyanka-Microsoft]

Purpose

This pull request expands the outputs in the infrastructure Bicep files to expose additional configuration values related to Azure OpenAI, Azure Search, and CosmosDB resources. These outputs will make it easier for downstream services and environments to access key parameters for deployment and integration.

Infrastructure output enhancements:

• infra/deploy_app_service.bicep: Added outputs for various Azure OpenAI configuration values (system messages, prompts, model, resource), Azure Search settings (index, service, query type, vector fields), and CosmosDB feedback enablement flag.
• infra/main.bicep: Propagated the new outputs from the app service and CosmosDB modules, including OpenAI prompts and settings, search service/index, CosmosDB configuration, and AI agent endpoint details.

Does this introduce a breaking change?

• Yes
• No

Golden Path Validation

• I have tested the primary workflows (the "golden path") to ensure they function correctly without errors.

Deployment Validation

• I have validated the deployment process successfully and all services are running as expected with this change.

What to Check

Verify that the following are valid

• I have built and tested the code locally and in a deployed app
• For frontend changes, I have pulled the latest code from main, built the frontend, and committed all static files.
• This is a change for all users of this app. No code or asset is specific to my use case or my organization.

Other Information