Fix up discrepancies between v1 and v2 package parsing

For Activity aliases, it's possible some values are already
set, which means they cannot be assumed to be 0, and can't be
overwritten if a attribute in the alias is undefined. For the
parsing v2 refactor, this was cleaned up to avoid
redundant != 0 checks, but those checks are indeed necessary.
This copies over the old logic and uses it exactly.

In some future cleanup, there should be a more structured way
of doing this, since it's not immediately obvious which values
are overridden or not. For example, description is always
overwritten even if no new value is provided in the alias.

This also fixes up the comparison tests and other bugs that
popped up because of them. The core issue was that when
auto-generating the dumpToString methods, the Alt+Insert
macro default selects all the fields in the current class,
but not all the parent classes, so some shared fields like
name/icon were not considered.

A notable case that was found when running the comparison tests
is that persistableMode is now "fixed" with v2. Previously,
a bug in PackageParser caused this value to be dropped if
the ActivityInfo object ever had to be copied. This is a change
from Q behavior, but there's no good way to reconcile this, and
it's better to be correct and consistent than broken, so this
fix was left in and excluded from the comparison tests.

Bug: 150106908

Test: manual run through steps in bug
Test: atest com.android.server.pm.parsing

Merged-In: I1301e28540314d0e643b73af7146c1a366eca6b5
Change-Id: I1301e28540314d0e643b73af7146c1a366eca6b5