This PR updates the `next/future/image` component so that CSS `filter` is never needed. Previously, we used SVG to blur for prod and CSS to blur for dev, but now we use SVG for both.
This required a shared function `getImageBlurSvg()` used between both client and server because `next dev` doesn't create Data URIs and instead defers blur generation until request time. So we also need to defer svg generation to request time (on the server) during next dev.
This is the first step to removing `<noscript>` completely (see #39736).
c3ceeb03ab