assistant2: Show accept terms UI in thread empty state (#23630)

<img
src="https://github.com/user-attachments/assets/cea93cfb-8a40-48c4-9d90-f1751c79603b"
width=400>



Release Notes:

- N/A

---------

Co-authored-by: Danilo <danilo@zed.dev>

crates/language_model/src/language_model.rs

@@ -245,12 +245,23 @@ pub trait LanguageModelProvider: 'static {
     fn must_accept_terms(&self, _cx: &AppContext) -> bool {
         false
     }
-    fn render_accept_terms(&self, _cx: &mut WindowContext) -> Option<AnyElement> {
+    fn render_accept_terms(
+        &self,
+        _view: LanguageModelProviderTosView,
+        _cx: &mut WindowContext,
+    ) -> Option<AnyElement> {
         None
     }
     fn reset_credentials(&self, cx: &mut AppContext) -> Task<Result<()>>;
 }
 
+#[derive(PartialEq, Eq)]
+pub enum LanguageModelProviderTosView {
+    ThreadEmptyState,
+    PromptEditorPopup,
+    Configuration,
+}
+
 pub trait LanguageModelProviderState: 'static {
     type ObservableEntity;