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/anthropic/Cargo.toml

@@ -5,6 +5,10 @@ edition = "2021"
 publish = false
 license = "AGPL-3.0-or-later"
 
+[features]
+default = []
+schemars = ["dep:schemars"]
+
 [lints]
 workspace = true
 
@@ -15,6 +19,8 @@ path = "src/anthropic.rs"
 anyhow.workspace = true
 futures.workspace = true
 http.workspace = true
+isahc.workspace = true
+schemars = { workspace = true, optional = true }
 serde.workspace = true
 serde_json.workspace = true