Adjust model selector popover design (#15056)

This PR mostly refines the model selector popover design by formatting
the models names' and adjusting spacing/alignment in the list-related
items. The list component changes could've been made in a separate PR
but it was also very practical to do it here as I was already
in-context. Either way, I'm happy to separate if that's better!

One thing I couldn't necessarily figure out, though, is why the order
changed (e.g., Anthropic at last ). I wonder if that was because of the
separator logic somehow? I'd love guidance here—new to Rust!

| Before | After |
|--------|--------|
| <img width="228" alt="Screenshot 2024-07-23 at 21 02 33"
src="https://github.com/user-attachments/assets/3372c6c9-08dc-4d71-9265-26f015e2dbc2">
| <img width="228" alt="Screenshot 2024-07-23 at 21 01 45"
src="https://github.com/user-attachments/assets/624cc7db-a3d9-48e3-99d7-c29829501130">
|

---

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
Co-authored-by: Bennet Bo Fenner <bennet@zed.dev>
Co-authored-by: Antonio <antonio@zed.dev>
Co-authored-by: Antonio Scandurra <me@as-cii.com>

crates/language_model/src/registry.rs

@@ -1,5 +1,5 @@
 use client::Client;
-use collections::HashMap;
+use collections::BTreeMap;
 use gpui::{AppContext, Global, Model, ModelContext};
 use std::sync::Arc;
 use ui::Context;
@@ -65,7 +65,7 @@ impl Global for GlobalLanguageModelRegistry {}
 
 #[derive(Default)]
 pub struct LanguageModelRegistry {
-    providers: HashMap<LanguageModelProviderId, Arc<dyn LanguageModelProvider>>,
+    providers: BTreeMap<LanguageModelProviderId, Arc<dyn LanguageModelProvider>>,
 }
 
 impl LanguageModelRegistry {
@@ -114,10 +114,8 @@ impl LanguageModelRegistry {
         }
     }
 
-    pub fn providers(
-        &self,
-    ) -> impl Iterator<Item = (&LanguageModelProviderId, &Arc<dyn LanguageModelProvider>)> {
-        self.providers.iter()
+    pub fn providers(&self) -> impl Iterator<Item = &Arc<dyn LanguageModelProvider>> {
+        self.providers.values()
     }
 
     pub fn available_models(&self, cx: &AppContext) -> Vec<Arc<dyn LanguageModel>> {
@@ -127,16 +125,6 @@ impl LanguageModelRegistry {
             .collect()
     }
 
-    pub fn available_models_grouped_by_provider(
-        &self,
-        cx: &AppContext,
-    ) -> HashMap<LanguageModelProviderId, Vec<Arc<dyn LanguageModel>>> {
-        self.providers
-            .iter()
-            .map(|(name, provider)| (name.clone(), provider.provided_models(cx)))
-            .collect()
-    }
-
     pub fn provider(
         &self,
         name: &LanguageModelProviderId,
@@ -160,7 +148,7 @@ mod tests {
 
         let providers = registry.read(cx).providers().collect::<Vec<_>>();
         assert_eq!(providers.len(), 1);
-        assert_eq!(providers[0].0, &crate::provider::fake::provider_id());
+        assert_eq!(providers[0].id(), crate::provider::fake::provider_id());
 
         registry.update(cx, |registry, cx| {
             registry.unregister_provider(&crate::provider::fake::provider_id(), cx);