Add CHANGE_HANDLE ioctl for drm gem v3

[David Francis]

This patch adds a new ioctl GEM_CHANGE_HANDLE which is needed by
amdgpu CRIU for dmabuf.

The ioctl allows a user to move a gem object to a new handle.

v2: Move documentation for this and other drm_gem ioctls to drm.h
v3: After testing with IGT, fixed return value on success

Accompanying changes:
kernel (for dmabuf CRIU support)
https://lists.freedesktop.org/archives/dri-devel/2025-June/510996.html
igt (for this ioctl)
https://gitlab.freedesktop.org/fdavid-amd/igt-gpu-tools
CRIU (for dmabuf CRIU support)
https://github.com/checkpoint-restore/criu/pull/2613