camel-core - Make it easier to get a route health-check by route id

When testing or the need to lookup a route health check then we should make this easier. The logic today is a bit cumbersome, with a stream of checks, etc.

HealthCheckRegistry hcr = context.getExtension(HealthCheckRegistry.class);
HealthCheckRepository repo = hcr.getRepository("routes").get();
HealthCheck hc = repo.stream().findFirst().get();