Use filter_packages to unbunden metalava

This change fixes a problem that entire framework source files are given
to metalava even when many of the source files are not for public. Using
the new property filter_packages, only source files that belongs to the
public packages are given to metalava.

This CL also changes the name of the filegroup 'framework-srcs' to
'framework-non-updatable-sources' to better describe its contents. In
addition, a build-time only library 'framework-all' is introduced. This
library produces a header jar for all framework sources for both
non-updatable and updatable parts. It is put to the classpath when
invoking metalava to give information on the hidden classes that were
filtered-out.

Bug: 140764681
Test: m
Change-Id: I6e16679109ac07820e35037754d4327442c014f2