Append LLNDK libraries in the APEX to the system linker config

Some of the LLNDK libraries are in the APEX, and those should be marked
as required libs of system image, so system namespaces can link to the
APEX namespace properly. This change automates the process instead of
adding APEX LLNDKs to linker.config.json manually.

Bug: 251782700
Test: Cuttlefish build and boot succeeded
Change-Id: I538a619caa67e64e6432517e1de87f3007bccbde