Add Setting kill switch for mic disclosure

Disable if mic disclosure if global settings
"sysui_mic_disclosure_enable" is 0. If the setting is not present -
enable.

Bug: 162308361
Test: adb shell appops start com.google.android.katniss 27 # indicator
comes up
      adb shell settings put global sysui_mic_disclosure_enable 0 #
indicator disappears
      adb shell appops stop com.google.android.katniss 27
      adb shell appops start com.google.android.katniss 27 # indicator
does not come up
      adb shell settings put global sysui_mic_disclosure_enable 1
      adb shell appops start com.google.android.katniss 27 # indicator
comes up

Change-Id: I7317fe58676615578a07f0b37ae5a8cd99db5576