Add support for interacting with Claude in the assistant panel (#11798)

Release Notes:

- Added support for interacting with Claude in the assistant panel. You
can enable it by adding the following to your `settings.json`:

    ```json
    "assistant": {
        "version": "1",
        "provider": {
            "name": "anthropic"
        }
    }
    ```

crates/assistant/src/assistant_panel.rs

@@ -800,6 +800,11 @@ impl AssistantPanel {
                 open_ai::Model::FourTurbo => open_ai::Model::FourOmni,
                 open_ai::Model::FourOmni => open_ai::Model::ThreePointFiveTurbo,
             }),
+            LanguageModel::Anthropic(model) => LanguageModel::Anthropic(match &model {
+                anthropic::Model::Claude3Opus => anthropic::Model::Claude3Sonnet,
+                anthropic::Model::Claude3Sonnet => anthropic::Model::Claude3Haiku,
+                anthropic::Model::Claude3Haiku => anthropic::Model::Claude3Opus,
+            }),
             LanguageModel::ZedDotDev(model) => LanguageModel::ZedDotDev(match &model {
                 ZedDotDevModel::Gpt3Point5Turbo => ZedDotDevModel::Gpt4,
                 ZedDotDevModel::Gpt4 => ZedDotDevModel::Gpt4Turbo,