Use the same InlineAssist action between both assistant and assistant2 (#22126)

This PR makes it so `assistant` and `assistant2` both use the same
action for inline assist (`zed_actions::InlineAssist`).

This makes it so the keybindings to deploy the inline assist seamlessly
swap based on the feature flag without needing to rebind them.

One minor caveat: if you're using `assistant2` the action name in the
command palette will be `assistant: inline assist`.

Release Notes:

- N/A

crates/zed/src/zed.rs

@@ -314,12 +314,13 @@ pub fn initialize_workspace(
             workspace_handle.update(&mut cx, |workspace, cx| {
                 if let Some(assistant_panel) = assistant_panel {
                     workspace.add_panel(assistant_panel, cx);
+                    workspace.register_action(assistant::AssistantPanel::inline_assist);
                 }
 
                 if let Some(assistant2_panel) = assistant2_panel {
                     workspace.add_panel(assistant2_panel, cx);
+                    workspace.register_action(assistant2::InlineAssistant::inline_assist);
                 }
-
             })
         })
         .detach();