Add filtering uninstalled package flag to the shouldFilterApplication

A lot of APIs in PackageManager return different results between an
unknown package and the package that is uninstalled in the current
user. An app can detect package's existence via this side-channel
leakage.

To fix these issues, this CL adds an extra flag to the
shouldFilterApplication() to support filtering uninstalled package.
APIs with the vulnerability can enable the flag when they invoke
application access filtering. (The fixes for those APIs are separated
into other CLs.)

Bug: 214394643
Test: atest AppEnumerationTests
Change-Id: I2875765b631c247539955c1d5dc864798e54896c