Method copy_buffer

Copy the `size` first bytes of `src` into `dst`. It's done using a command buffer allocated from `command_pool`. The command buffer is cubmitted tp `transfer_queue`.

(
        device: &Device,
        command_pool: vk::CommandPool,
        transfer_queue: vk::Queue,
        src: vk::Buffer,
        dst: vk::Buffer,
        size: vk::DeviceSize,
    )