agent: Fix opening configuration view from the model selector (#28154)

This PR fixes an issue where opening the configuration view from the
model selector in the Agent (or inline assist) was not working properly.

Fixes https://github.com/zed-industries/zed/issues/28078.

Release Notes:

- Agent Beta: Fixed an issue where selecting "Configure" in the model
selector would not bring up the configuration view.

crates/zed_actions/src/lib.rs

@@ -183,12 +183,21 @@ pub mod icon_theme_selector {
     impl_actions!(icon_theme_selector, [Toggle]);
 }
 
+pub mod agent {
+    use gpui::actions;
+
+    actions!(agent, [OpenConfiguration]);
+}
+
 pub mod assistant {
     use gpui::{actions, impl_actions};
     use schemars::JsonSchema;
     use serde::Deserialize;
 
-    actions!(assistant, [ToggleFocus, OpenPromptLibrary]);
+    actions!(
+        assistant,
+        [ToggleFocus, OpenPromptLibrary, ShowConfiguration]
+    );
 
     #[derive(Clone, Default, Deserialize, PartialEq, JsonSchema)]
     #[serde(deny_unknown_fields)]