Introduce uses-native-library tag

Since Android 7.0, partners were able to export some of their native
shared libraries to apps. So far, the native libraries were provided to
all apps regardless of whether they are actually needed or not. Even
worse, it was impossible to prevent the installation of an app to the
device where the some (or all) of the required native libs don't exist;
the apps had to manually handle the case, which sometimes impossible
when the dependency is so fundamental.

This change introduces a new tag <uses-native-library> to the app
manifest. Similary to the existing <uses-library> tag which is for
(java) shared libraries, the new tag is used to describe the depedencies
to the native shared libraries.

Apps targeting Android S or higher are required to use the tag to import
the native shared libraries. Libraries that are not depended on won't be
available to the app even if the libraries are listed in the
public.libraries*.txt files. Furthermore, when the dependency can't be
satisfied for an app, the package manager refejects installing the app.

The dependency can be optional using the `android:required` attribute.
When it is set to true, the absence of the lib on the device doesn't
prevent the app from being installed. However, the app has to gracefully
deal with the absence.

The changed behavior only affects apps targeting S or higher. Existing
apps are unaffected; they still get all the public native libraries
regardless of whether they have <uses-native-library> tags or not; the
tags are simply ignored.

This is the first version of the implementation and therefore needs
further refinements. The followings are two major TODOs.

1) The native shared lib dependencies of the java shared libraries
are not enforced. For example, if an app depends on a java shared
library foo and foo depends on some native shared libraries, the
classloader where code from foo is loaded still gets all native shared
libraries. This should be fixed.

2) New APIs should be added. SharedLibraryInfo should be extended to
represent native shared libraries. The meaning of
ApplicationInfo.sharedLibraryFiles should be revised. Finally, the new
tag should be made public.

Bug: 142191088
Test: atest CtsUsesNativeLibraryTest
Change-Id: Iceb038aa86872d23e9faf582ae91b1fdcaf5c64c