Autogenerate connectivity jarjar rules

Jarjar rules are hard to keep in sync with code, and hard to maintain
manually as the distinction between what should and should not be
jarjared is not always clear. This results in unsafe binaries that are
manually maintained, and developer frustration when something fails due
to incorrect jarjar rules.

Autogenerate jarjar rules at build time instead. This is achieved by
introducing a jarjar-rules-generator python-based library, which scans
pre-jarjar intermediate artifacts, and outputs jarjar rules for every
class to put it in a package specific to the module. The only exceptions
are:

 - Classes that are API (module-lib API is the largest API surface of
   the module)
 - Classes that have unsupportedappusage symbols
 - Classes that are excluded manually (for example, because they have
   hardcoded external references, like for
   ConnectivityServiceInitializer in SystemServer).

This change causes all classes in framework-connectivity(-t) and
service-connectivity to be jarjared into android.net.connectivity, but
still avoids jarjaring classes in com.android.server as before, to keep
it small.
For many classes this differs from the original jarjar rule.

Notes on implementation:

 - connectivity-jarjar-rules now has a subset
   framework-connectivity-jarjar-rules containing only the rules
   necessary for framework-connectivity. This is necessary because
   framework-connectivity cannot depend on rules generated based on
   service-connectivity, as there would be a dependency cycle
   (service-connectivity depends on framework-connectivity); Soong even
   crashes with a stack overflow.

 - framework-wifi.stubs.module_lib is added to
   framework-connectivity-pre-jarjar as it is necessary to build it (it
   is already in impl_only_libs in the defaults).
   It is unclear why framework-connectivity-pre-jarjar could build
   before that (possibly because it was only used as "lib" ?)

 - Fix package-private visibility; for example NattSocketKeepalive,
   TcpSocketKeepalive are not API so should be jarjared, but are used
   by ConnectivityManager which is not jarjared, so they are not in the
   same package after the change. Package-private members in the
   former 2 need to be public to be accessible. Changes in this commit
   are all that is needed, as demonstrated by followup commits that move
   the classes to a different package without further changes, and that
   enforce that no class in an API package gets jarjared.

 - framework-connectivity-internal-test-defaults is separated from
   framework-connectivity-test-defaults, for unit tests that need to
   access internal jarjared classes. Such tests need to use the jarjar
   rules themselves too, so this is only appropriate for connectivity
   internal unit tests.

Test: atest ConnectivityCoverageTests CtsNetTestCases
Bug: 217129444
Change-Id: Ied17c3955ea2fda130089265d02908937ad8af1e

framework/src/android/net/QosSocketInfo.java

@@ -73,9 +73,10 @@ public final class QosSocketInfo implements Parcelable {
      * The parcel file descriptor wrapped around the socket's file descriptor.
      *
      * @return the parcel file descriptor of the socket
+     * @hide
      */
     @NonNull
-    ParcelFileDescriptor getParcelFileDescriptor() {
+    public ParcelFileDescriptor getParcelFileDescriptor() {
         return mParcelFileDescriptor;
     }