Introduce DISALLOW_BLUETOOTH_SHARING.

When this restriction is enforced Bluetooth sharing option should not be
present when the user tries to share something. Previously this was handled
by explicitly disabling bluetooth sharing activity during managed
provisioning, now this code is to be removed (see topic CLs) and the same
behavior should be achieved by setting this restriction for profile owners
by default.

In Bluetooth:
1) Don't check restrictions on boot, it is invoked anyway through the
  listener during boot.
2) Ignore when the restriction is "changed" from true to true - i think
  it was the initial intent in that condition.
3) Disable the component for a particular user and not always the
  system user. This is something that has to be fixed in O I think since
  currently in secondary user the bluetooth itself gets disabled but the
  sharing thing still shows up.

In DPMS:
1) Now ActiveAdmin for PO also contains a set of restrictions applied by
  default.
2) Now all ActiveAdmins for POs are loaded quite early. That shouldn't
  have huge impact though.

Bug: 36249732
Test: run cts -m CtsDevicePolicyManagerTestCases -t com.android.cts.devicepolicy.ManagedProfileTest#testBluetoothSharingRestriction
Test: run cts -m CtsDevicePolicyManagerTestCases -t com.android.cts.devicepolicy.DeviceOwnerTest#testBluetoothRestriction
Test: runtest --path frameworks/base/services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerServiceMigrationTest.java
Change-Id: I78c4ffbd503c4a10138e8c0862a9f206f24c5631