It seems useful to have the flexibility to remap "enter" in confirmations to
"y", but keep "enter" for menus and suggestions (even though we sometimes use
menus as confirmations, but it's still good to give users the choice).
So far, confirmations and prompts were handled by the same view, context, and
controller, with a bunch of conditional code based on whether the view is
editable. This was more or less ok so far, since it does save a little bit of
code duplication; however, now we need separate views, because we don't have
dynamic keybindings, but we want to map "confirm" to different keys in
confirmations (the "universal.confirm" user config) and prompts (hard-coded to
enter, because it doesn't make sense to customize it there).
It also allows us to get rid of the conditional code, which is a nice benefit;
and the code duplication is actually not *that* bad.
For custom commands it is useful to select an earlier command and have it copied
to the prompt for further editing. This can be done by hitting 'e' now.
For other types of suggestion panels we don't enable this behavior, as you can't
create arbitrary new items there that don't already exist as a suggestion.
In the custom commands panel you can now tab to the suggestions and hit 'd' to
delete items from there. Useful if you mistyped a command and don't want it to
appear in your history any more.
