Merge "Wait for disconnect when rebooting to userspace FB" into main

void reboot_to_userspace_fastboot() {

    fb->RebootTo("fastboot");

    if (fb->WaitForDisconnect() != fastboot::SUCCESS) {

        die("Error waiting for USB disconnect.");

    }

    fb->set_transport(nullptr);

    // Give the current connection time to close.

    // Not all platforms support WaitForDisconnect. There also isn't a great way to tell whether

    // or not WaitForDisconnect is supported. So, just wait a bit extra for everyone, in order to

    // make sure that the device has had time to initiate its reboot and disconnect itself.

    std::this_thread::sleep_for(std::chrono::seconds(1));

    fb->set_transport(open_device());