Change ToolOutput to ToolView (#11682)

Additionally, the internal `ToolView` trait used by the registry is now
called `InternalToolView`.

This should make it a bit easier to understand that the `ToolView` is
intended for a `gpui::View` (implementing `Render`). It does still feel
like more could be merged here but I think the built tools are now a bit
clearer.

Release Notes:

- N/A

crates/assistant_tooling/src/assistant_tooling.rs

@@ -8,6 +8,6 @@ pub use attachment_registry::{
 };
 pub use project_context::ProjectContext;
 pub use tool_registry::{
-    LanguageModelTool, SavedToolFunctionCall, ToolFunctionCall, ToolFunctionDefinition, ToolOutput,
-    ToolRegistry,
+    LanguageModelTool, SavedToolFunctionCall, ToolFunctionCall, ToolFunctionDefinition,
+    ToolRegistry, ToolView,
 };