Framework and system_server classes can access public vendor libraries

This CL fixes a regression caused by [1] which introduced
<uses-native-library> tag [2]. With the change, public vendor libraries
[3] became accessible only when they are listed in the caller's
AndroidManifest.xml using the new tag. However, this caused a problem to
the places where AndroidManifest.xml doesn't exist: framework and
system_server classes. For those cases, [1] incorrectly used a null list
as the requested native libraries, and as a result, no public vendor
libraries were accessible.

This CL fixes the issue by not doing the filtering for the class loaders
created for non-app contexts like zygote or system_server. Specifically,
it uses the magic keyword "ALL" which let libnativeloader.so
accept all public vendor libraries.

[1] https://android.googlesource.com/platform/frameworks/base/+/6a5b8b1f6db172b5aaadcec0c3868e54e214b675
[2] https://developer.android.com/guide/topics/manifest/uses-native-library-element
[3] https://source.android.com/devices/tech/config/namespaces_libraries#adding-additional-native-libraries

Bug: 205164833
Test: libcuttlefish_fs.so is loaded when built with the other CLs in the
same topic

Change-Id: Id92c59642773851d70d05a05f43eb5873e9de86b