[detectors/dynatrace] Contribute dynatrace detector from resourcedetectionprocessor #8958

Problem Statement

collector-contrib/processor/resourcedetectionprocessor/internal/dynatrace implements a resource detector that reads resource attributes from the Dynatrace enrichment files injected by the OneAgent. There is currently no equivalent in go-contrib/detectors/, which means Dynatrace detection is only available to collector-contrib pipelines and not to any Go SDK user.

Proposed Solution

Add a new detectors/dynatrace package implementing the Dynatrace 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/dynatrace
• Tracking issue: [processor/resourcedetection] Align detectors with opentelemetry-go SDK detectors opentelemetry-collector-contrib#48159

Additional Context

What the collector-contrib detector does:

• Reads Dynatrace-injected enrichment files (indirection files and attribute files) from well-known filesystem paths.
• Emits attributes such as dt.entity.process_group_instance, host.name, host.id, and other Dynatrace-specific resource attributes.