Generate block list info file of .img files

This is a text file with block size information of the contents of the
.img files. build_image supports creating this as an implicit output.
This CL creates the build rule to generate this output. This
will be copied to IMAGES/ subdir of target_files.zip

There is a subtle difference between the make and soong implementation.
In make, we generate two $partiton.img files. One is hermetic (for
targret_files.zip), and other is non-hermetic (for adb sync). The block
file is generated from the hermetic one.

OTOH, in the soong implementation, we are generating the block file from
the non-hermetic one. This should not matter, since pinning the
timestamp should not have an effect on block sizes. This implementation
detail can be changed in a follow up CL if necessary.

Test: diff'd target_files.zip locally, all $partition.map files are
identical
Bug: 388635097

Change-Id: I984d4fb55071296a82dae38ef09be6804ff0f3ae