vim: Retain search direction upon search submit (#16754)

Before, when using `?` and `#` for backwards search it would initially
search for the previous match, but upon subsequent inputs to `n` and
`N`, `n` is always treated as "forward" and `N` is always treated as
"backward", instead of continuing the search direction.

now, if i use `?` or `#` for backward search, `n` will go to the
previous selection, and `N` will go to the next. Functionality stays the
same for `/` and `*`.

Release Notes:

- vim: Fixed `n` direction after searching backwards

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/test_data/test_backwards_n.json

@@ -0,0 +1,8 @@
+{"Put":{"state":"ˇa b a b a b a"}}
+{"Key":"*"}
+{"Key":"n"}
+{"Get":{"state":"a b a b ˇa b a","mode":"Normal"}}
+{"Key":"#"}
+{"Get":{"state":"a b ˇa b a b a","mode":"Normal"}}
+{"Key":"n"}
+{"Get":{"state":"ˇa b a b a b a","mode":"Normal"}}