Visibility checks for checkPackage and watchingMode

This change adds a check for app visibility to calls to checkPackage and
startWatchingMode to ensure that the subject package name should be
visible to the caller before taking action.

Test: atest AppOpTests CtsAppOpsTestCases
Bug: 179047153
Change-Id: I8a5b2e355656a5409f6712d8d131adc7873f2f14