[detectors/scaleway] Contribute scaleway detector from resourcedetectionprocessor #8967

Problem Statement

collector-contrib/processor/resourcedetectionprocessor/internal/scaleway implements a resource detector for Scaleway Instances. There is currently no equivalent in go-contrib/detectors/, which means Scaleway detection is only available to collector-contrib pipelines and not to any Go SDK user.

Proposed Solution

Add a new detectors/scaleway package implementing the Scaleway detector as a resource.Detector, ported from the collector-contrib implementation, so that collector-contrib/processor/resourcedetectionprocessor can delegate to it and any other Go SDK user can adopt it.

Prior Art

• Collector-contrib implementation to port from: processor/resourcedetectionprocessor/internal/scaleway
• Tracking issue: [processor/resourcedetection] Align detectors with opentelemetry-go SDK detectors opentelemetry-collector-contrib#48159

Additional Context

What the collector-contrib detector does:

• Queries the Scaleway Instance Metadata API.
• Emits: cloud.provider (scaleway), cloud.platform (scaleway_baremetal or scaleway_instance), cloud.region, cloud.availability_zone, host.id, host.name, host.type.