FIX: Re-add the x r and x t for dismiss new/posts and dismiss topics

Re-applied the keyboard bindings for 'x r' and 'x t' to support dismiss new/posts and dismiss topics. They were accidentally removed when I had to rebase my PR.
https://meta.discourse.org/t/new-updated-bar-and-dismiss-new-button-unreachable-by-keyboard/18946/10?u=cpradio