GitLab

Summary:
Function to join a list of cameras objects into a single batched object.

FB: In the next diff I will remove the `concatenate_cameras` function in implicitron and update the callsites.

Reviewed By: nikhilaravi

Differential Revision: D33198209

fbshipit-source-id: 0c9f5f5df498a0def9dba756c984e6a946618158