rightmost meta-columns showing offscreen column names/values

From @frosencrantz in #3148:

I sometimes have a wide table, with lots of columns, that cannot all fit on the screen. I have wondered if it would be useful to have 2 right most columns that show the 1) names and 2) values of the current row of the columns not visible to the right either because they don't fit or they are hidden. It would be possible to see more of the data that is available. This would break the table formatting, and might also be counterintuitive for most users. It would allow more data to fit on the screen.

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