Improve model selection in the assistant (#12472)

https://github.com/zed-industries/zed/assets/482957/3b017850-b7b6-457a-9b2f-324d5533442e


Release Notes:

- Improved the UX for selecting a model in the assistant panel. You can
now switch model using just the keyboard by pressing `alt-m`. Also, when
switching models via the UI, settings will now be updated automatically.

crates/anthropic/Cargo.toml

@@ -23,6 +23,7 @@ isahc.workspace = true
 schemars = { workspace = true, optional = true }
 serde.workspace = true
 serde_json.workspace = true
+strum.workspace = true
 
 [dev-dependencies]
 tokio.workspace = true

crates/anthropic/src/anthropic.rs

@@ -4,11 +4,12 @@ use http::{AsyncBody, HttpClient, Method, Request as HttpRequest};
 use isahc::config::Configurable;
 use serde::{Deserialize, Serialize};
 use std::{convert::TryFrom, time::Duration};
+use strum::EnumIter;
 
 pub const ANTHROPIC_API_URL: &'static str = "https://api.anthropic.com";
 
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
-#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, EnumIter)]
 pub enum Model {
     #[default]
     #[serde(alias = "claude-3-opus", rename = "claude-3-opus-20240229")]