Use a block decoration for entering rename text

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/theme/src/theme.rs

@@ -278,6 +278,8 @@ pub struct EditorStyle {
     pub gutter_padding_factor: f32,
     pub active_line_background: Color,
     pub highlighted_line_background: Color,
+    pub diff_background_deleted: Color,
+    pub diff_background_inserted: Color,
     pub line_number: Color,
     pub line_number_active: Color,
     pub guest_selections: Vec<SelectionStyle>,
@@ -383,6 +385,8 @@ impl InputEditorStyle {
             gutter_padding_factor: Default::default(),
             active_line_background: Default::default(),
             highlighted_line_background: Default::default(),
+            diff_background_deleted: Default::default(),
+            diff_background_inserted: Default::default(),
             line_number: Default::default(),
             line_number_active: Default::default(),
             guest_selections: Default::default(),