For die-hard fuzzy-searching fans it's probably in the way, so taking it out
makes fuzzy filtering work better. For substring filtering it always retains the
sort order anyway.
For some lists it is useful to keep the same sort order when filtering (rather
than sorting by best match like we usually do). Add an optional function to
FilteredList to make this possible, and use it whenever we show lists of things
sorted by date (branches, stashes, reflog entries), as well as menu items
because this allows us to keep the section headers in the keybindings menu,
which is useful for understanding what you are looking at when filtering.
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.
