java_sdk_library: Add redirection to module-lib stubs

Previously, when using sdk_version: "module_current" any direct
reference to an sdk library would use the public not module-lib stubs.
This change corrects that.

Prior to the addition of the module-lib api scope almost all
java_sdk_library instances supported all the scopes to which a request
for jars could be redirected, i.e. public, system and test. The
exceptions to that are a few special instances that were used with
sdk_version: "none" and so were either caught by the java_sdk_library
special cases or dropped through to public.

The addition of module-lib, plus the flexible control over which scopes
are generated means that is no longer true. It is possible for a
java_sdk_library to be requested for a scope it does not have which
would have resulted in an empty set of paths being returned leading to
confusing compilation errors.

To avoid that this change also adds support for using the inheritance
hierarchy defined by the apiScope.extends field to fall back to the
closest available surface.

Test: m nothing
Bug: 155164730
Change-Id: I6aab75a772433ee0a36b6f1758a4aec4be2f9a49