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/language/src/buffer.rs

@@ -75,6 +75,8 @@ pub enum Capability {
     ReadOnly,
 }
 
+pub type BufferRow = u32;
+
 /// An in-memory representation of a source code file, including its text,
 /// syntax trees, git status, and diagnostics.
 pub struct Buffer {
@@ -3104,7 +3106,7 @@ impl BufferSnapshot {
     /// row range.
     pub fn git_diff_hunks_in_row_range(
         &self,
-        range: Range<u32>,
+        range: Range<BufferRow>,
     ) -> impl '_ + Iterator<Item = git::diff::DiffHunk<u32>> {
         self.git_diff.hunks_in_row_range(range, self)
     }