Add Spring Boot Smoke Test

Spring Boot packages its apps in [a unique way](https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-executable-jar-format.html), and loads dependencies using a custom ClassLoader that makes them invisble to the System Class Loader which the agent uses at premain to discover useful dependencies like Trace ID injection libraries. More generally, we've had issues specific to spring boot in the past and should have a way to smoke test Spring Boot apps.

See OTel Java Instrumentation Spring Boot smoke tests for reference: https://github.com/open-telemetry/opentelemetry-java-instrumentation/tree/67371ecfc9fc9b4cf7985ae96ffc5bde9a246b11/smoke-tests/springboot

Inizia esaminando gli OpenTelemetry Java Instrumentation Spring Boot smoke tests collegati nell’issue, quindi ispeziona questo repository per individuarne la struttura esistente degli smoke test e gli entry point dell’agent. Aggiungi uno Spring Boot smoke test che eserciti l’agent nella configurazione di Spring Boot con executable-jar e custom-ClassLoader; il lavoro è completo quando lo smoke test viene eseguito correttamente e copre la dependency discovery, come Trace ID injection.

Scritto dal modello di indicizzazione a partire dal testo della issue.