Skeleton
The camera is animated using these character curves:- Camera_Pitch
- Camera_Yaw
- Camera_Roll

Example of camera animation curves.
Meshes and Animations
You can find camera animations in the Camera folder of each weapon. While these sequences are not used directly in the game, they were used via the extraction tool, that transferred camera curves to the character animation:
Camera Motion Extractor.
Camera Animator
This Actor Component applies animations to the camera:
Extract character curves, rotate the camera.