Generate SDK docs for v7 support library packages.

This change required fixing some bugs in how AAPT handles
qualified symbols such as "android:layout_height"
when generating JavaDoc links.  The links were being
generated using the package name of the generated R file
rather than the package name of the referenced symbol.
These broken links caused the JavaDoc build to fail.

Bug: 8175766
Change-Id: I52fbef27825a25abca960cb44b59c2132267e9d6