Remove `woff` font support in favor of `woff2` only

## Is your feature request related to a problem?
At this time, all modern browsers support `woff2` fonts.  Therefore, there is no need to continue support within nvQuickTheme for preloading `woff` fonts.

## Describe the solution you'd like
Remove support for preloading `woff` fonts.

## Describe alternatives you've considered
n/a

## Additional context
n/a