Change the DefaultAvatar’s size to a more reasonable size of 128x128 pixels.
Throughout the Suite Core avatars are usually embedded via the `getImageTag` function
but when using the direct avatar URL a larger image is usually wanted.
Firefox for example does not upscale images used in `window.Notification`
thus the avatar would be rendered as a tiny 16x16 image in this case.
This change allows to downscale accordingly in this case.
// the <path> is basically a shorter version of a <rect>
$svg = <<<SVG
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" width="16" height="16"><path fill="#{$backgroundColor}" d="M0 0h16v16H0z"/><text x="8" y="8" fill="#{$textColor}" text-anchor="middle" dy=".3em" font-family="Arial" font-size="7">{$text}</text></svg>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16" width="128" height="128"><path fill="#{$backgroundColor}" d="M0 0h16v16H0z"/><text x="8" y="8" fill="#{$textColor}" text-anchor="middle" dy=".3em" font-family="Arial" font-size="7">{$text}</text></svg>
SVG;
$this->src = "data:image/svg+xml;base64," . base64_encode($svg);