Use same link style in HTML messages
Use same link style in HTML messages

Links in HTML messages were missing the usual underline style, making them
look different from links in text messages (which already do this).

Fixes vector-im/riot-web#4655.

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk