Add Image Optimizer format counting metrics
Real-time analytics and Historical Stats responses now include the following new metrics: imgopto_avif_count, imgopto_jpeg_count, imgopto_png_count, imgopto_gif_count, imgopto_webp_count, imgopto_jpegxl_count, imgopto_svg_count, imgopto_mp4_count.
Prior change: Add Alerts derived rate metrics for Compute responses
