Updated the color of the reply button to be more neutral

The primaryTextColor wasn't a good fit, because it was
drawing too much attention being pure black. We're now
taking the default color instead. It's also used for
active permissions now.

Test: add notification, look at reply button.
Change-Id: If390c66e927a92a1115250abb7254fafe81b054c
Fixes: 72750728