Expose check write setting operation as system API

If tethering provisioning check is required, caller must have tethering
privilege permission to change tethering. If provisioning is not needed,
caller who has write settings permisssion also can change tethering.
Expose checkAndNoteWriteSettingsOperation for tethering check whether
caller has write settings permission.

Bug: 144814607
Test: -build, flash, boot
      -atest SettingsTest#testCheckWriteSettingsOperation
Change-Id: Ib3931bbe39361c2c4324935f16473cc675848032