Support system.img modification for inter branch target

Add support for modifying the system.img to work with older
Android versions for inter branch build targets such as P GSI on
O-MR1 device.

modify_system_img.sh is a script based off of
change_security_path_ver.sh, but uses the
build/make/tools/releasetools/add_img_to_target_files.py script
instead of mounting and unsparsing image with simg2img, so that
the script can be run on Android build servers without root
permission.

Bug: 79153114
Test: development/vndk/tools/build_mixed -v 8.1.0
-m development/vndk/tools/modify_system_img.sh
out/prebuilts_cached/artifacts/gsi
out/prebuilts_cached/artifacts/walleye $DIST_DIR
out/host/linux-x86/bin/checkvintf

Merged-In: I5bd5b55a1b948dc5d394e5c74d4d11e3127d7385
Change-Id: I5bd5b55a1b948dc5d394e5c74d4d11e3127d7385
(cherry picked from commit 20296c0a)