Add soong config variables of paths of *_dlkm partitions and whether they are built for a product.

Update prebuilt_etc to use these variable so fs_config_dirs and fs_config_files could be installed to *_dlkm partitions.

Bug: 377304441
Test: lunch aosp_cf_x86_64_phone-trunk_staging-eng && m, check fs_config_dirs
and fs_config_files exist in etc/ in each partitions

Change-Id: Ic90267f6b3fd60674bb27016cf5f31fc2614e35b