Don't offer the BT sharing option to the user if BT is disallowed.

Disable BluetoothOppLauncherActivity component if the
UserManager#BLUETOOTH_DISALLOWED user restriction is set.

Test: cts-tradefed run cts -m CtsDevicePolicyManagerTestCases --test
com.android.cts.devicepolicy.DeviceOwnerTest#testBluetoothRestriction

Bug: 32895060
Bug: 34239380

Change-Id: I3467c82881896f276f542583bb50807b5e27276b