Add stubs for sun... classes for hiddenapi

Adds stubs for ojluni/src/main/java/sun classes some of whose hidden
members are used by applications. Each such member is annotated with
the UnsupportedAppUsage annotation.

The stubs are built as part of the core-oj-hiddenapi target from which
the build will extract information about the hidden class members that
are used by applications.

This was tested by making and then manually checking that the generated
out/target/common/obj/PACKAGING/hiddenapi-light-greylist.txt was the
same (after sorting) before and after this change.

Test: see above
Bug: 117818301
Change-Id: Ieef82c0f7a9951b7ba22af92b19038d424e4d8b8