Don't claim we have bluetooth access until the user grants location

permissions.  This fixes an ugly behavior when for when the user does
a from scratch install and first runs the app (and the dialog comes up
to grant access).

Previously we were starting our BLE scan for devices before that dialog
has been approved by the user, which Android doesn't return an error for
it instead just silently refuses to show devices.  If the user switched
away from the app and came back, we'd restart our scan and they could see
their device.

This fixes things so that the user doesn't have to switch away from our
app once before the devices appear.

app/src/main/java/com/geeksville/mesh/ui/SettingsFragment.kt

@@ -518,7 +518,7 @@ class SettingsFragment : ScreenFragment("Settings"), Logging {
 
     override fun onResume() {
         super.onResume()
-        if (!hasCompanionDeviceApi)
+        if (!hasCompanionDeviceApi && model.bluetoothEnabled.value!!)
             scanModel.startScan()
     }
 }