[Object Detection] Add DETR Model

[DavidLandup0]

Draft PR for observability. Body will be updated as progress is made.

DETR Elements

Will include:

• DETR layers
  • Positional embeddings
  • Frozen BatchNormalization
  • DETRTransformerEncoder
  • DETRTransformerDecoder
• DetrBackbone (Modified ResNet)
• Object detection preprocessor
• DETRObjectDetector (Tying the above into a class)
• Weight conversion script from https://huggingface.co/facebook/detr-resnet-50

... and relevant workflows, collab notebooks, etc. for sanity checking.

[DavidLandup0]

Getting there :)
Lots of refactoring to do, but the core modules are there and work nicely with each other.