OpenTelemetry Traceparent Propagation from Container to Aspire AppHost

Aspire AppHost (main solution):
```
var builder = DistributedApplication.CreateBuilder(args);
var env = builder.AddDockerComposeEnvironment("docker-compose")
.ConfigureComposeFile(f =>
{
// other stuff
});

// Some other projects connected as AddProject (works fine)

var testContainer = builder.AddContainer("test", "container_address", "master")
.WithOtlpExporter()
.PublishAsDockerComposeService((resource, service) =>
{
service.ExtraHosts = new()
{
{"host.docker.internal", "host-gateway"}
};
})
.WithComputeEnvironment(env);

builder.Build().Run();
```

TestContainer Program.cs (separate project):
```
var builder = Host.CreateApplicationBuilder(args);

builder.Logging.AddOpenTelemetry(options =>
{
options.IncludeScopes = true;
options.IncludeFormattedMessage = true;
});

builder.Services.AddOpenTelemetry()
.WithMetrics(metrics =>
{
metrics.AddMeter("BaseMeter");
})
.WithTracing(tracingBuilder =>
{
tracingBuilder
.AddSource("BaseSource")
.AddHttpClientInstrumentation();
})
.UseOtlpExporter();
```

What am I doing wrong? Why don’t I see Tracing/Metrics from TestContainer in the Aspire AppHost Dashboard?

Start with the Aspire AppHost configuration and the separate TestContainer Program.cs shown in the issue. Trace how the OTLP exporter and Docker Compose environment are configured, then verify the resulting container telemetry against the Aspire AppHost Dashboard; done means the TestContainer's traces and metrics appear there.

Written by the indexing model from the issue text.