ext4_utils: allow passing flash block sizes to make_ext4fs_sparse functions

Add versions of make_ext4fs_sparse_fd() and
make_ext4fs_sparse_fd_directory() that accept flash erase & logical
block size as arguments. Refactor to avoid copied code in the new
aligned versions of each function.

Test: Pass block sizes to new functions using fastboot -w and check
that the new userdata has the correct stride and stripe-width values.
Bug: 33243520
Signed-off-by: Connor O'Brien <connoro@google.com>

Change-Id: I16da6e0ce699439c53d1a722c6d56eb3f9cd9bc5
2 files changed