RFC: Prefer integrated GPUs over discrete GPUs by default?

Currently, mpv's ra_vk picks the physical device based on the following priority list:

    static const struct m_opt_choice_alternatives types[] = {
        {"discrete",   VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU},
        {"integrated", VK_PHYSICAL_DEVICE_TYPE_INTEGRATED_GPU},
        {"virtual",    VK_PHYSICAL_DEVICE_TYPE_VIRTUAL_GPU},
        {"software",   VK_PHYSICAL_DEVICE_TYPE_CPU},
        {"unknown",    VK_PHYSICAL_DEVICE_TYPE_OTHER},
        {0}
    };

It was suggested that perhaps integrated GPUs should be above discrete GPUs by default, so that users of dual-GPU systems (typically laptops?) would use the more power-friendly integrated by default. This might be more in line with what's expected of a media player. I was personally thinking that we'd always want to use the fastest GPU so users can use the highest quality settings.

I'm not sure what users expect the default to be here. Opinions?

Start at mpv's ra_vk physical-device selection and review the current priority list shown in the issue. Read the discussion to determine whether integrated or discrete GPUs should be preferred by default; the work is complete only after the default policy is agreed and its behavior is defined.