Add language_models crate to house language model providers (#20945)

This PR adds a new `language_models` crate to house the various language
model providers.

By extracting the provider definitions out of `language_model`, we're
able to remove `language_model`'s dependency on `editor`, which improves
incremental compilation when changing `editor`.

Release Notes:

- N/A

crates/language_models/src/language_models.rs

@@ -0,0 +1,80 @@
+use std::sync::Arc;
+
+use client::{Client, UserStore};
+use fs::Fs;
+use gpui::{AppContext, Model, ModelContext};
+use language_model::{LanguageModelProviderId, LanguageModelRegistry, ZED_CLOUD_PROVIDER_ID};
+
+mod logging;
+pub mod provider;
+mod settings;
+
+use crate::provider::anthropic::AnthropicLanguageModelProvider;
+use crate::provider::cloud::{CloudLanguageModelProvider, RefreshLlmTokenListener};
+use crate::provider::copilot_chat::CopilotChatLanguageModelProvider;
+use crate::provider::google::GoogleLanguageModelProvider;
+use crate::provider::ollama::OllamaLanguageModelProvider;
+use crate::provider::open_ai::OpenAiLanguageModelProvider;
+pub use crate::settings::*;
+pub use logging::report_assistant_event;
+
+pub fn init(
+    user_store: Model<UserStore>,
+    client: Arc<Client>,
+    fs: Arc<dyn Fs>,
+    cx: &mut AppContext,
+) {
+    crate::settings::init(fs, cx);
+    let registry = LanguageModelRegistry::global(cx);
+    registry.update(cx, |registry, cx| {
+        register_language_model_providers(registry, user_store, client, cx);
+    });
+}
+
+fn register_language_model_providers(
+    registry: &mut LanguageModelRegistry,
+    user_store: Model<UserStore>,
+    client: Arc<Client>,
+    cx: &mut ModelContext<LanguageModelRegistry>,
+) {
+    use feature_flags::FeatureFlagAppExt;
+
+    RefreshLlmTokenListener::register(client.clone(), cx);
+
+    registry.register_provider(
+        AnthropicLanguageModelProvider::new(client.http_client(), cx),
+        cx,
+    );
+    registry.register_provider(
+        OpenAiLanguageModelProvider::new(client.http_client(), cx),
+        cx,
+    );
+    registry.register_provider(
+        OllamaLanguageModelProvider::new(client.http_client(), cx),
+        cx,
+    );
+    registry.register_provider(
+        GoogleLanguageModelProvider::new(client.http_client(), cx),
+        cx,
+    );
+    registry.register_provider(CopilotChatLanguageModelProvider::new(cx), cx);
+
+    cx.observe_flag::<feature_flags::LanguageModels, _>(move |enabled, cx| {
+        let user_store = user_store.clone();
+        let client = client.clone();
+        LanguageModelRegistry::global(cx).update(cx, move |registry, cx| {
+            if enabled {
+                registry.register_provider(
+                    CloudLanguageModelProvider::new(user_store.clone(), client.clone(), cx),
+                    cx,
+                );
+            } else {
+                registry.unregister_provider(
+                    LanguageModelProviderId::from(ZED_CLOUD_PROVIDER_ID.to_string()),
+                    cx,
+                );
+            }
+        });
+    })
+    .detach();
+}