Separate VNDK libs into another linker namespace

This commit extracts /system/lib[64]/vndk and /system/lib[64]/vndk-sp
into another namespace in the vendor section.  This commit is necessary
because LLNDK libraries (e.g. libc or libnativewindow) may otherwise
link to the shared libraries in /system/lib[64]/vndk-sp, which may be
older than the one LLNDK libraries built with.

Test: aosp_walleye boots
Bug: 70816018
Change-Id: I6fceb0da92c978ad940af91f5efe84e673c9247e