Update SVG styles for Windows High Contrast Mode

[carrythebanner]

Chrome v89 changed how they handle SVGs in Windows High Contrast Mode (WinHCM). (See https://bugs.chromium.org/p/chromium/issues/detail?id=1164162 and w3c/csswg-drafts#4915 for origin of behavior change.)

As a result, our SVG icons aren't getting the user's high contrast theme color assignments as they previously did. This affects Chrome and Edge, and presumably any other Chromium-based browser. (Firefox continues to work as-expected.)

We can add CSS styles to enforce the intended behavior, something like:

@media (-ms-high-contrast: active), (forced-colors: active) {
  svg.icon {
    -ms-high-contrast-adjust: auto;
    forced-color-adjust: auto;
  }
}

[carrythebanner]

This is how our SVGs (icons, Shift logo in upper left) render in the latest Chrome/Edge with WinHCM enabled:

This is how Firefox renders them, which is how Chrome/Edge used to and what I am expecting: