com.android.cts.stub is growing very large. Split apart some of
the popular components into separate static libraries. This
should allow packages to depend on the components they need
rather than all of cts.stub.
Current code at the moment doesn't have to be changed, because
I have CtsTestStubs depending on these new shared libraries.
However, change the net package to depend on the ctstestserver
static library as a proof of concept rather than including
its source directly.
Change-Id: I32c54eab3ddfb1d4391d6ffc347fbc9cb2fe97f9
248128f2a9