Prevent wifi scan throttling on Android 9 (Pie) with NETWORK_SETTINGS permission

Unfortunately that's a signature level permission reserved only for system applications:

<!-- Allows Settings and SystemUI to call methods in Networking services
     <p>Not for use by third-party or privileged applications.
     @hide This should only be used by Settings and SystemUI.
-->
<permission android:name="android.permission.NETWORK_SETTINGS"
    android:protectionLevel="signature" />

Source: https://github.com/aosp-mirror/platform_frameworks_base/blob/master/core/res/AndroidManifest.xml

It is rumoured that Android Q will have a new permission android.permission.ACCESS_BACKGROUND_LOCATION that allows background scanning. The docs say it "Allows an app to access location in the background." The protection level is "dangerous" rather than "signature".