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/open_ai/Cargo.toml

@@ -20,3 +20,4 @@ isahc.workspace = true
 schemars = { workspace = true, optional = true }
 serde.workspace = true
 serde_json.workspace = true
+strum.workspace = true

crates/open_ai/src/open_ai.rs

@@ -4,8 +4,8 @@ use http::{AsyncBody, HttpClient, Method, Request as HttpRequest};
 use isahc::config::Configurable;
 use serde::{Deserialize, Serialize};
 use serde_json::{Map, Value};
-use std::time::Duration;
-use std::{convert::TryFrom, future::Future};
+use std::{convert::TryFrom, future::Future, time::Duration};
+use strum::EnumIter;
 
 pub const OPEN_AI_API_URL: &str = "https://api.openai.com/v1";
 
@@ -44,7 +44,7 @@ impl From<Role> for String {
 }
 
 #[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 {
     #[serde(rename = "gpt-3.5-turbo", alias = "gpt-3.5-turbo-0613")]
     ThreePointFiveTurbo,