[UWP] Links are no longer underlined

[paulcam206]

Not sure if this is an intentional AdaptiveCards change, an OS change, or something else, but the test app is no longer rendering links with an underline in current master:

[RebeccaAnne]

Looks like this is a regression from #3308

[paulcam206]

Looks like this is a regression from #3308

tricksy. guessing it's here and here?