Add manifest for oneplus nord

<?xml version="1.0" encoding="UTF-8"?>

<manifest>

  <project path="device/oneplus/avicii" remote="e" name="e/devices/android_device_oneplus_avicii" />

  <project path="device/oneplus/common" remote="github" name="LineageOS/android_device_oneplus_common" />

  <project path="kernel/oneplus/sm7250" remote="github" name="LineageOS/android_kernel_oneplus_sm7250" />

</manifest>