Add support for multiple resource providers in ResourceNotificationService

[Copilot]

This PR implements support for aggregating resources from multiple providers simultaneously, enabling teams to monitor both Docker containers and Kubernetes pods through a single Aspire Dashboard interface.

Problem

Previously, the application only supported a single resource provider at a time, configured via "ResourceProvider": "docker" or "ResourceProvider": "k8s". This limitation prevented users from monitoring hybrid environments with both Docker containers and Kubernetes workloads.

Solution

Implemented a new ResourceNotificationService that acts as an aggregator for multiple IResourceProvider instances:

Key Changes

1. New Service Architecture

   • Created IResourceNotificationService interface for provider aggregation
   • Implemented ResourceNotificationService that combines multiple providers
   • Maintains full backward compatibility with existing IResourceProvider interface

2. Enhanced Configuration Support

   // Single provider (existing - still works)
   {
     "ResourceProvider": "docker"
   }
   
   // Multiple providers (new capability)
   {
     "ResourceProviders": ["docker", "k8s"],
     "KubernetesResourceProviderConfiguration": {
       "Namespace": "production",
       "Servicenames": "redis;rabbitmq"
     }
   }

3. Resource Aggregation

   • Merges initial resources from all enabled providers
   • Combines real-time change streams using Channel<T> for efficient multiplexing
   • Maintains resource-to-provider mapping for intelligent log routing

4. Robust Error Handling

   • Individual provider failures don't affect other providers
   • Graceful handling of provider lifecycle events
   • Comprehensive logging with structured LoggerMessage delegates

Testing

• Added comprehensive unit tests for service registration scenarios
• Created integration tests for resource aggregation and log routing
• Verified backward compatibility with existing single-provider configurations
• Manual testing confirms application starts correctly with both single and multiple provider configs

Example Usage

With this change, users can now monitor their entire infrastructure through a single dashboard:

# View both Docker containers and K8s pods in unified interface
curl http://localhost:7007/info
# Returns aggregated resources from all configured providers

The implementation ensures that log requests are automatically routed to the correct provider based on resource names, providing a seamless experience regardless of where the resource is hosted.

Fixes #38.

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