Add ICU's .dat to the runtime APEX

Add ICU's .dat to the runtime APEX

There are associated changes in libcore
to reference the new location instead of /system.
There is an associated change in external/icu
to remove the /system copy of the file.

This reverts commit a91d654f.
This is a reapply of commit 3b231900

Bug: 120853401
Bug: 119293618
Test: build / boot
Change-Id: I2e250795a58787b5b625c1cc68aa4bfffd11c6a8