Improve Responsiveness of Icons

[amalnanavati]

Building off of this commit message.

Currently, the app's solution to scaling SVG icons within buttons is to pass in iconWidth and iconHeight which is hardcoded as a percentage of the overall screen width/height. However, this won't work well if we render components in a smaller part of the screen, e.g., what we do when customizing distance to mouth in a smaller modal. Hence, the more robust solution to responsiveness of icon size is to make both the width and height a percentage of the icon's flexbox parts (se the above-linked commit for an example).