Check pm install/uninstall --user command

Currently, if the specified user of install command doesn't exist,
the system will crash. We should check the command valid and call
system method.

Bug: 297376291
Test: manual. Can install without correct parameter and show error
message if user doesn't exist
Test: atest PackageManagerShellCommandInstallTest
Test: atest PackageManagerShellCommandMultiUserTest

Change-Id: I7595257a5e69dd9fff4d46dfb76f0d3ca14a78b7