[KSP2] Resolver.getDeclarationsFromPackage() returns declarations from the default package when passing in an unknown package

[kuanyingchou]

When getting the declarations from an unknown package like this:

resolver.getDeclarationsFromPackage("does.not.exist")

KSP 1 returns an empty Sequence while KSP 2 returns declarations from the default package.

Tested with 42217b8 and 2.0.0-Beta3-1.0.18-20240207.110119-15.