Disable extension entries when the corresponding dev extension is installed (#10580)

This PR updates the extension list to disable remote entries when the
corresponding dev extension is installed.

Here is what this looks like:

<img width="1189" alt="Screenshot 2024-04-15 at 4 09 45 PM"
src="https://github.com/zed-industries/zed/assets/1486634/48bb61d4-bc85-4ca6-b233-716831dfa7d8">


Release Notes:

- Disabled extension entries when there is a development copy of that
extension installed.

crates/extensions_ui/src/components/extension_card.rs

@@ -4,15 +4,22 @@ use ui::prelude::*;
 
 #[derive(IntoElement)]
 pub struct ExtensionCard {
+    overridden_by_dev_extension: bool,
     children: SmallVec<[AnyElement; 2]>,
 }
 
 impl ExtensionCard {
     pub fn new() -> Self {
         Self {
+            overridden_by_dev_extension: false,
             children: SmallVec::new(),
         }
     }
+
+    pub fn overridden_by_dev_extension(mut self, overridden: bool) -> Self {
+        self.overridden_by_dev_extension = overridden;
+        self
+    }
 }
 
 impl ParentElement for ExtensionCard {
@@ -34,7 +41,24 @@ impl RenderOnce for ExtensionCard {
                 .border_1()
                 .border_color(cx.theme().colors().border)
                 .rounded_md()
-                .children(self.children),
+                .children(self.children)
+                .when(self.overridden_by_dev_extension, |card| {
+                    card.child(
+                        h_flex()
+                            .absolute()
+                            .top_0()
+                            .left_0()
+                            .occlude()
+                            .size_full()
+                            .items_center()
+                            .justify_center()
+                            .bg(theme::color_alpha(
+                                cx.theme().colors().elevated_surface_background,
+                                0.8,
+                            ))
+                            .child(Label::new("Overridden by dev extension.")),
+                    )
+                }),
         )
     }
 }