Build repeatable system images with mke2fs.

We have added support in mkuserimg_mke2fs.sh that allows specifying
filesystem UUID and hash seed UUID. This CL generates and passes the
UUIDs based on the image name and build fingerprint. This way we can
rebuild and get identical images.

Note that this only applies to images generated with `m dist` and with
signing tools (sign_target_files_apks.py and
add_img_to_target_files.py). Images under $OUT (built with `make`) are
not affected.

Bug: 64994964
Test: lunch marlin-userdebug; run `m dist` twice (after deleting the
      intermediate files under $OUT/obj/PACKAGING), and compare the
      generated images.
Change-Id: I41cf4e5869582bb930af2f35a8e9c79bff43b2a2