language_model: Add supports_tools method to LanguageModel (#27867)

This PR adds a new `supports_tools` method to the `LanguageModel` trait
to indicate whether a given model supports tool use.

Release Notes:

- N/A

crates/language_model/src/fake_provider.rs

@@ -153,6 +153,10 @@ impl LanguageModel for FakeLanguageModel {
         provider_name()
     }
 
+    fn supports_tools(&self) -> bool {
+        false
+    }
+
     fn telemetry_id(&self) -> String {
         "fake".to_string()
     }

crates/language_model/src/language_model.rs

@@ -185,6 +185,9 @@ pub trait LanguageModel: Send + Sync {
         LanguageModelAvailability::Public
     }
 
+    /// Whether this model supports tools.
+    fn supports_tools(&self) -> bool;
+
     fn tool_input_format(&self) -> LanguageModelToolSchemaFormat {
         LanguageModelToolSchemaFormat::JsonSchema
     }