title_bar: Remove dependency on extensions_ui (#20929)

This PR removes a dependency on the `extensions_ui` from the `title_bar`
crate.

This dependency only existed to reference the `Extensions` action, which
has now been moved to the `zed_actions` crate.

This allows `title_bar` to move up in the crate dependency graph.

Release Notes:

- N/A

crates/extensions_ui/Cargo.toml

@@ -44,6 +44,7 @@ util.workspace = true
 vim.workspace = true
 wasmtime-wasi.workspace = true
 workspace.workspace = true
+zed_actions.workspace = true
 
 [dev-dependencies]
 editor = { workspace = true, features = ["test-support"] }

crates/extensions_ui/src/extensions_ui.rs

@@ -38,12 +38,12 @@ use crate::extension_version_selector::{
     ExtensionVersionSelector, ExtensionVersionSelectorDelegate,
 };
 
-actions!(zed, [Extensions, InstallDevExtension]);
+actions!(zed, [InstallDevExtension]);
 
 pub fn init(cx: &mut AppContext) {
     cx.observe_new_views(move |workspace: &mut Workspace, cx| {
         workspace
-            .register_action(move |workspace, _: &Extensions, cx| {
+            .register_action(move |workspace, _: &zed_actions::Extensions, cx| {
                 let existing = workspace
                     .active_pane()
                     .read(cx)