Ctrl-R should allow pasting from a register when typing a command, as in insert mode

[J-Fields]

Is your feature request related to a problem? Please describe.
Not very often that I want to do this, to be honest. It's nice to have the option though.

Describe the solution you'd like
As in vim, Ctrl-R should act the same on the command line as in insert mode.

Describe alternatives you've considered
Ctrl-V currently works to paste from clipboard, but not from an arbitrary register.

[ThomasRLane]

I want to do this fairly often, to paste the filename of the file I'm editing into the :e command, and go to a similarly-named file. Or, sometimes, when I edit a file under a path that leads far from the rest of what I'm editing, and then want to edit a different file in that same faraway directory.

[J-Fields]

#3034