Description

This PR adds the Panoptic Deeplab architecture described in Panoptic-DeepLab

Type of change

• A new research paper code implementation

Tests

• python -m official.vision.beta.projects.panoptic_maskrcnn.modeling.heads.panoptic_deeplab_heads_test
• python -m official.vision.beta.projects.panoptic_maskrcnn.modeling.factory_test
• python -m official.vision.beta.projects.panoptic_maskrcnn.modeling.panoptic_deeplab_model_test
• python -m official.vision.beta.projects.panoptic_maskrcnn.modeling.layers.panoptic_deeplab_merge_test
• python -m official.vision.beta.projects.panoptic_maskrcnn.tasks.panoptic_deeplab_test

Checklist

• I have signed the Contributor License Agreement.
• I have read guidelines for pull request.
• My code follows the coding guidelines.
• I have performed a self code review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.