Fix dumpsys package parser bugs

Address previous code review comments.

Stop using 'dumpsys package <pkg>' syntax, since its not possible
to distinguish cases where package does not exist and cmd fails.

Instead, always dump all packages and then lookup info for
individual package.

Bug 9377138

Change-Id: Ia1784a1ca4b40c9db7d1f7ef08209f195ec58c12
3 files changed