Add malloc_dump_to_file() and malloc_log_to_file() functions to write heap dumps and malloc traffic logs to host files. This is useful for debugging memory leaks in sandbox by allowing comparison of before/after heap states with external tools like diff. These functions are only available in sandbox builds since they use host-filesystem access. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com>