Kenames like `Control-n` or `meta-p` should not be quoted or they don't work. Keyseqs like `\C-p` or `ab` must continue to be quoted. See also: https://www.gnu.org/software/bash/manual/html_node/Readline-Init-File-Syntax.html Fixes https://github.com/nix-community/home-manager/issues/3611
Also add a basic test case.