Introduce DisplayRow, MultiBufferRow newtypes and BufferRow type alias (#11656)

Part of https://github.com/zed-industries/zed/issues/8081

To avoid confusion and bugs when converting between various row `u32`'s,
use different types for each.
Further PRs should split `Point` into buffer and multi buffer variants
and make the code more readable.

Release Notes:

- N/A

---------

Co-authored-by: Piotr <piotr@zed.dev>

crates/vim/src/test.rs

@@ -6,7 +6,7 @@ mod vim_test_context;
 use std::time::Duration;
 
 use command_palette::CommandPalette;
-use editor::DisplayPoint;
+use editor::{display_map::DisplayRow, DisplayPoint};
 use futures::StreamExt;
 use gpui::{KeyBinding, Modifiers, MouseButton, TestAppContext};
 pub use neovim_backed_binding_test_context::*;
@@ -235,7 +235,7 @@ async fn test_selection_on_search(cx: &mut gpui::TestAppContext) {
         let highlights = editor.all_text_background_highlights(cx);
         assert_eq!(3, highlights.len());
         assert_eq!(
-            DisplayPoint::new(2, 0)..DisplayPoint::new(2, 2),
+            DisplayPoint::new(DisplayRow(2), 0)..DisplayPoint::new(DisplayRow(2), 2),
             highlights[0].0
         )
     });