Diff View: Scroll to center of hunks when reviewing (#25846)

When reviewing hunks, scroll to put them at the center of the screen
so you can better see the context around that hunk.

The field `center_cursor` was added to the actions `editor::GoToHunk`
and `editor::GoToPrevHunk`, this was set to `false` by default in
keymaps, as it wouldn't help with in-editor navigation.

The field is set to `true` for when you trigger `git::StageAndNext`
and `git::UnstageAndNext`, this is also `true` for the buttons in the
Diff View toolbar.

Release Notes:

- N/A

crates/editor/src/actions.rs

@@ -189,6 +189,20 @@ pub struct DeleteToPreviousWordStart {
     pub ignore_newlines: bool,
 }
 
+#[derive(PartialEq, Clone, Deserialize, Default, JsonSchema)]
+#[serde(deny_unknown_fields)]
+pub struct GoToHunk {
+    #[serde(default)]
+    pub center_cursor: bool,
+}
+
+#[derive(PartialEq, Clone, Deserialize, Default, JsonSchema)]
+#[serde(deny_unknown_fields)]
+pub struct GoToPrevHunk {
+    #[serde(default)]
+    pub center_cursor: bool,
+}
+
 #[derive(PartialEq, Clone, Deserialize, Default, JsonSchema)]
 pub struct FoldAtLevel(pub u32);
 
@@ -218,6 +232,8 @@ impl_actions!(
         ExpandExcerptsDown,
         ExpandExcerptsUp,
         FoldAt,
+        GoToHunk,
+        GoToPrevHunk,
         HandleInput,
         MoveDownByLines,
         MovePageDown,
@@ -300,11 +316,9 @@ gpui::actions!(
         GoToDefinition,
         GoToDefinitionSplit,
         GoToDiagnostic,
-        GoToHunk,
         GoToImplementation,
         GoToImplementationSplit,
         GoToPrevDiagnostic,
-        GoToPrevHunk,
         GoToTypeDefinition,
         GoToTypeDefinitionSplit,
         HalfPageDown,