double-press go-right to cross into hidden columns

From the #3148 thread. @frosencrantz:

I feel using the right key it sometimes becomes a little to easy to get into the hidden columns. Those times I think it would be great if there was some sort of tactile feedback to let me know I jumped over the line.

@midichef proposed requiring two consecutive presses of go-right to cross from the last visible column into the hidden columns, with a status message on the first press; prototype visidatarc in https://github.com/saulpw/visidata/issues/3148#issuecomment-4763246205. @frosencrantz tried it: "I need to try it some more, but I like it."

[this issue written by Claude Fable 5 and approved by @saulpw]