FindContextID generates a random number between 3 and max uint32
and uses it as context ID.
Using ioctl findContextID checks if the context ID is free, if
the context ID is being used by other process, this function
iterates from over all valid context IDs until one is available.
`/dev/vhost-vsock` is used to check what context IDs are free,
we need it to ensure we are using a unique context ID to
create the vsocks.
Signed-off-by: Julio Montes <julio.montes@intel.com>
