[GSOC][WIP] Proposal: Fractal Markers Detection API

[Roaa-838]

Proposed Fractal Markers Detection API

implementation of hierarchical fractal markers proposal based on:
📄 "Fractal Markers: A New Approach for Long-Range Marker Pose Estimation Under Occlusion"
(Romero-Ramirez et al., IEEE Access 2019)

what this does

• A simple API that detects markers in parent-child relationships (See full Doxygen docs in the header file)

Key Features:
✅ Unified Detection - Finds parent+child markers together
✅ Occlusion Resistant - Needs only 2 visible child markers
✅ Multi-Scale - Works from 640x480 to 1080p resolutions

Next Steps Needed:
I'd appreciate guidance on:

1. Best practices for implementing FractalDictionary --> Should FractalDictionary extend Dictionary?
2. Integration with existing Aruco test infrastructure

Pull Request Readiness Checklist

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• Target branch: opencv_contrib 4.x
• Will add tests if proposal is accepted
• Needs documentation expansion