chore: use Cow instead of String for tooltips (#2838)

A QoL change to align `Tooltip` with other elements like `Label`
Release Notes:

- N/A

crates/workspace/src/pane.rs

@@ -303,10 +303,10 @@ impl Pane {
                         let tooltip_label;
                         if pane.is_zoomed() {
                             icon_path = "icons/minimize_8.svg";
-                            tooltip_label = "Zoom In".into();
+                            tooltip_label = "Zoom In";
                         } else {
                             icon_path = "icons/maximize_8.svg";
-                            tooltip_label = "Zoom In".into();
+                            tooltip_label = "Zoom In";
                         }
 
                         Pane::render_tab_bar_button(
@@ -1477,7 +1477,7 @@ impl Pane {
         index: usize,
         icon: &'static str,
         is_active: bool,
-        tooltip: Option<(String, Option<Box<dyn Action>>)>,
+        tooltip: Option<(&'static str, Option<Box<dyn Action>>)>,
         cx: &mut ViewContext<Pane>,
         on_click: F1,
         on_down: F2,