diffimg: binary tool for comparing images (#9668)

This tool uses existing libraries: image, imageio, imageio-lite,
imagediff to perform difference comparison for on-disk images.

We refactor renderdiff to use this tool instead of using
python dependencies.


Co-authored-by: Ben Doherty <bendoherty@google.com>

test/renderdiff/generate.sh

@@ -31,7 +31,7 @@ function start_render_() {
         python3 -m venv ${VENV_DIR}
         source ${VENV_DIR}/bin/activate
 
-        NEEDED_PYTHON_DEPS=("numpy" "tifffile")
+        NEEDED_PYTHON_DEPS=()
         for cmd in "${NEEDED_PYTHON_DEPS[@]}"; do
             if ! python3 -m pip show -q "${cmd}"; then
                 python3 -m pip install ${cmd}