Fix llndk_library init

llndk_library modules were not calling module.Init(), which caused them
not to register ModuleBase.VendorProperties.  Unregistered property
structs lose their values during cloning, which caused the shared
variants of llndk_library modules to not have IsLLNDK set.

Call module.Init(), which registers ModuleBase.VendorProperties.  Also
add a helper function to filter out llndk_library modules that now
show up in the list of modules with IsLLNDK set.

Bug: 170784825
Test: m checkbuild
Change-Id: Iafde85f6a95e85a618f6f7d7a210398febb6b158