feat(opentelemetry): add resource configuration support

[Dzheky]

Description

Adds support for custom resource attributes configuration in the OpenTelemetry plugin, enabling users to specify additional resource metadata like deployment.environment, service.instance.id, and other custom attributes.

Example

{
  //...
  openTelemetry: {
    exporters: [createOtlpHttpExporter({ url: 'http://localhost:4318' })],
    serviceName: 'my-gateway',
    resource: {
      'deployment.environment': 'production',
      'service.instance.id': process.env.HOSTNAME,
      'service.namespace': 'platform',
      'service.name': 'custom-service-name', // Overrides serviceName
    },
  }
  //...
}

Why

Previously, users could only configure service.name via the serviceName option. This limitation made it difficult to add essential resource attributes like deployment environment, instance IDs, or custom metadata that are needed for proper observability and trace correlation in production environments.

Related Issues
#1149

[enisdenjo]

@EmrysMyrddin care to take a look? Is this something we'll have in v2?

[EmrysMyrddin]

Yes, this is something that will be possible in v2. I'm currently working on configuration changes!

Anyway, it is already possible, you can disable automatic sdk initialization and do your own OTEL setup. I would recommend this over the automatic configuration for a production configuration, it will give you the full control of OTEL behavior.

[Dzheky]

@EmrysMyrddin This is how we currently did this, it would be still nice to have this in automatic initialisation. So should this PR be closed and it will be implemented in v2?