Autogenerate a system_dlkm android_filesystem

This .img file will package the .ko files returned by
`BOARD_SYSTEM_KERNEL_MODULES` (plus some other files). The .ko files
will be clustered by directory, and a `prebuilt_kernel_modules` will
be automatically created for each cluster. These will then be added to
the deps of the top-level system_dlkm android_filesystem.

Bug: 376726109
Test: m out/soong/.intermediates/build/soong/fsgen/soong_filesystem_creator/android_common/diff_test_aosp_cf_x86_64_phone_generated_system_dlkm_image.txt
KATI only installed file(s):
  etc/NOTICE.xml.gz
  etc/build.prop
  etc/fs_config_dirs
  etc/fs_config_files

Change-Id: I96669ad9595379c4de4c67331fc56bfa8d93e036