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"
        }
    }
    ```

Cargo.lock

@@ -225,6 +225,8 @@ dependencies = [
  "anyhow",
  "futures 0.3.28",
  "http 0.1.0",
+ "isahc",
+ "schemars",
  "serde",
  "serde_json",
  "tokio",
@@ -332,6 +334,7 @@ dependencies = [
 name = "assistant"
 version = "0.1.0"
 dependencies = [
+ "anthropic",
  "anyhow",
  "chrono",
  "client",