SVG Icons are fuzzy on high DPI displays

This is coming from my forum post: https://forum.qt.io/topic/133166/svgs-used-for-button-icons-are-fuzzy-on-highdpi-devices

I didn't see any replies to it.  Google searching didn't reveal much of any other results...

—

I'm building an app right now that targets Android and iOS.  Typically these devices are high DPI (e.g. `Screen.devicePixelRatio` will return a value higher than `1.0`).  On these screens, when I use an SVG file for a `ToolButton` and `Button`'s `icon.source`, I'm seeing these "fuzzy" SVGs.  When they are far away from the user, they might not notice, but when they look up close, they might be able to see the issue.

Attached is a screenshot from my LG Q7+.  Notice how the text on the Button is nice and crisp, but the SVG looks really bad.  Like it was rasterized and a lower resolution and then up scaled.

The SVG files I'm using come from Google's Material Design iconset, which are known to be "good" SVGs so they should not have any issues.

Part of the point of using SVGs is that they scale seamlessly; they are not doing so in Qt right now.