Add a new SDK member type java_systemserver_libs.

Similar to java_boot_libs, java_systemserver_libs only provide access
to their dex implementation jar for use by dexpreopting and do not
provide an actual implementation jar.

This is used in the subsequent CL.

Bug: 194150908
Test: m nothing
Change-Id: Ib2e7d5e6c002314a0231f46934a766f4a27e610a