Add POC OpenTelemetry instrumentation for Solid Process

[tomascco]

Bring Rails-like, first class monitoring and instrumentation to your app's service layer.

Solid Process is intended to be used based on the application needs, only on complex business logic. Having first class support for instrumentation and monitoring is essential.

This pull request adds a simple OpenTelemetry/Grafana stack to the project. It also includes Proof of Concept instrumentation for Solid Process.

To do:

• Emit Active Support instrumentation events
• Create OpenTelemetry spans for each Solid Processes' step
• Add span attributes
• Add span status

To run the POC:

1. Run the compose file
2. Run the rails server
3. Navigate on the app (http://localhost:3000) to generate some traces
4. Go to the Grafana Explore tab (http://localhost:3001/explore) and inspect the generated traces.

Before:

After: