vim: Fix relative line motion

Before this change up and down were in display co-ordinates, after this
change they are in fold coordinates (which matches the vim behaviour).

To make this work without causing usabliity problems, a bunch of extra
keyboard shortcuts now work:

- vim: `z {o,c}` to open,close a fold
- vim: `z f` to fold current visual selection
- vim: `g {j,k,up,down}` to move up/down a display line
- vim: `g {0,^,$,home,end}` to get to start/end of a display line

Fixes: zed-industries/community#1562

crates/vim/src/test/neovim_connection.rs

@@ -41,6 +41,7 @@ pub enum NeovimData {
     Key(String),
     Get { state: String, mode: Option<Mode> },
     ReadRegister { name: char, value: String },
+    SetOption { value: String },
 }
 
 pub struct NeovimConnection {
@@ -222,6 +223,29 @@ impl NeovimConnection {
         );
     }
 
+    #[cfg(feature = "neovim")]
+    pub async fn set_option(&mut self, value: &str) {
+        self.nvim
+            .command_output(format!("set {}", value).as_str())
+            .await
+            .unwrap();
+
+        self.data.push_back(NeovimData::SetOption {
+            value: value.to_string(),
+        })
+    }
+
+    #[cfg(not(feature = "neovim"))]
+    pub async fn set_option(&mut self, value: &str) {
+        assert_eq!(
+            self.data.pop_front(),
+            Some(NeovimData::SetOption {
+                value: value.to_string(),
+            }),
+            "operation does not match recorded script. re-record with --features=neovim"
+        );
+    }
+
     #[cfg(not(feature = "neovim"))]
     pub async fn read_register(&mut self, register: char) -> String {
         if let Some(NeovimData::Get { .. }) = self.data.front() {