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.
Something dumb that we're currently doing is expecting list items
to define an ID method which returns a string. We use that when copying
items to clipboard with ctrl+o and when getting a ref name for diffing.
This commit gets us a little deeper into that hole by explicitly requiring
list items to implement that method so that we can easily use the new
helper functions in list_controller_trait.go.
In future we need to just remove the whole ID thing entirely but I'm too
lazy to do that right now.
We don't need it there so no need to enable it.
I'm leaving the disabled reason checks there, even though they're now redundant,
because they're only one-liners and they communicate intent.
The only time we should call SetSelectedLineIdx is when we are happy for a
select range to be retained which means things like moving the selected line
index to top top/bottom or up/down a page as the user navigates.
But in every other case we should now call SetSelection because that will
set the selected index and cancel the range which is almost always what we
want.
This begins a big refactor of moving more code out of the Gui struct into contexts, controllers, and helpers. We also move some code into structs in the
gui package purely for the sake of better encapsulation
