Cut the dependency to framework from droiddoc modules

droiddoc modules for the SDK API documentation and stubs library
generations have depended on the 'framework' (which was recently changed
to framework-minus-apex' module to get the list of Java source files to
be processed.

This however caused a circular dependency when we tried to modularize
some classes in the framework library as a separate library. The
separate java library depended on the stubs library (because it should
only use SDK APIs) and the stubs library depended on the framework
library. The framework library itself depended on the separated library
(or its stub) to use APIs from the separated library, thus forming a
circular dependency.

This change fixes the problem by directly giving the framework source
files via a filegroup `framework-sources-to-document` where all Java
and AIDL files that are to be documented are included in.

This change also put the generated R.java and Manifest.java files from
framework-res into the filegroup for framework sources.

Bug: 70046217
Bug: 135922046
Test: m

Change-Id: I09ad88da47540d31ad089aad5e1151a4b6877ec2