Use svgicon for scrolltrack

[mhui]

Looks slightly different but close enough. This is so we don't have to import ic-font

[codecov]

Codecov Report

Merging #354 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #354   +/-   ##
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  Coverage   82.22%   82.22%           
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  Files          59       59           
  Lines        1221     1221           
  Branches      218      218           
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  Hits         1004     1004           
  Misses        165      165           
  Partials       52       52

[wfro]

LGTM - more Icon => SVGIcon conversions are always welcome.

Let's test this one using yarn link (I can help with that, I haven't done it in a while myself so I need a refresher anyways) first since it's one of the more used components. I don't think there'll be any issues but can't hurt.