Change behaviour of screen capture disabled

Background
* Historically, when the screen capture disabled
  policy was set on the personal profile, screen
  capture was disabled for the whole device
  (per-device).
* This should be changed to only be disabled in
  the personal profile (per-profile).

Changes
* Renamed DevicePolicyCache methods to setScreenCaptureAllowed
  and isScreenCaptureAllowed
* Added parameter ownerCanAddInternalSystemWindow to
  isScreenCaptureAllowed

Bug: 148453838
Bug: 157035400
Test: atest com.android.server.devicepolicy.DevicePolicyManagerTest
Change-Id: If1bd68f0ec3e88497c5d3b4382977b526b2364ba