agent: Render diffs for the edit file tool (#29234)

This PR implements the `ToolCard` for the edit file tool, which allow us
to display an editor with a diff in the thread view with the changes
performed by the model.

- [x] Fix buffer sometimes displaying empty
- [x] Stop buffer from scrolling together with the thread
- [x] Fix multibuffer header sometimes appearing
- [x] Fix buffer height issue
- [x] Implement "full height" expand button
- [x] Add "Jump To File" functionality
- [x] Polish and refine styles

Release Notes:

- agent: Added diff preview cards in the thread view for edits performed
by the agent.

---------

Co-authored-by: João Marcos <marcospb19@hotmail.com>
Co-authored-by: Richard Feldman <oss@rtfeldman.com>
Co-authored-by: Agus Zubiaga <hi@aguz.me>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/editor/src/editor.rs

@@ -433,6 +433,8 @@ pub enum EditorMode {
         scale_ui_elements_with_buffer_font_size: bool,
         /// When set to `true`, the editor will render a background for the active line.
         show_active_line_background: bool,
+        /// When set to `true`, the editor's height will be determined by its content.
+        sized_by_content: bool,
     },
 }
 
@@ -441,6 +443,7 @@ impl EditorMode {
         Self::Full {
             scale_ui_elements_with_buffer_font_size: true,
             show_active_line_background: true,
+            sized_by_content: false,
         }
     }
 
@@ -798,6 +801,8 @@ pub struct Editor {
     show_breadcrumbs: bool,
     show_gutter: bool,
     show_scrollbars: bool,
+    disable_scrolling: bool,
+    disable_expand_excerpt_buttons: bool,
     show_line_numbers: Option<bool>,
     use_relative_line_numbers: Option<bool>,
     show_git_diff_gutter: Option<bool>,
@@ -1589,11 +1594,13 @@ impl Editor {
             blink_manager: blink_manager.clone(),
             show_local_selections: true,
             show_scrollbars: true,
+            disable_scrolling: true,
             mode,
             show_breadcrumbs: EditorSettings::get_global(cx).toolbar.breadcrumbs,
             show_gutter: mode.is_full(),
             show_line_numbers: None,
             use_relative_line_numbers: None,
+            disable_expand_excerpt_buttons: false,
             show_git_diff_gutter: None,
             show_code_actions: None,
             show_runnables: None,
@@ -16175,11 +16182,21 @@ impl Editor {
         cx.notify();
     }
 
+    pub fn disable_scrolling(&mut self, cx: &mut Context<Self>) {
+        self.disable_scrolling = true;
+        cx.notify();
+    }
+
     pub fn set_show_line_numbers(&mut self, show_line_numbers: bool, cx: &mut Context<Self>) {
         self.show_line_numbers = Some(show_line_numbers);
         cx.notify();
     }
 
+    pub fn disable_expand_excerpt_buttons(&mut self, cx: &mut Context<Self>) {
+        self.disable_expand_excerpt_buttons = true;
+        cx.notify();
+    }
+
     pub fn set_show_git_diff_gutter(&mut self, show_git_diff_gutter: bool, cx: &mut Context<Self>) {
         self.show_git_diff_gutter = Some(show_git_diff_gutter);
         cx.notify();