collab: Setup database for LLM service (#15882)

This PR puts the initial infrastructure for the LLM service's database
in place.

The LLM service will be using a separate Postgres database, with its own
set of migrations.

Currently we only connect to the database in development, as we don't
yet have the database setup for the staging/production environments.

Release Notes:

- N/A

crates/collab/src/llm.rs

@@ -1,10 +1,12 @@
 mod authorization;
+pub mod db;
 mod token;
 
 use crate::api::CloudflareIpCountryHeader;
 use crate::llm::authorization::authorize_access_to_language_model;
+use crate::llm::db::LlmDatabase;
 use crate::{executor::Executor, Config, Error, Result};
-use anyhow::Context as _;
+use anyhow::{anyhow, Context as _};
 use axum::TypedHeader;
 use axum::{
     body::Body,
@@ -24,11 +26,31 @@ pub use token::*;
 pub struct LlmState {
     pub config: Config,
     pub executor: Executor,
+    pub db: Option<Arc<LlmDatabase>>,
     pub http_client: IsahcHttpClient,
 }
 
 impl LlmState {
     pub async fn new(config: Config, executor: Executor) -> Result<Arc<Self>> {
+        // TODO: This is temporary until we have the LLM database stood up.
+        let db = if config.is_development() {
+            let database_url = config
+                .llm_database_url
+                .as_ref()
+                .ok_or_else(|| anyhow!("missing LLM_DATABASE_URL"))?;
+            let max_connections = config
+                .llm_database_max_connections
+                .ok_or_else(|| anyhow!("missing LLM_DATABASE_MAX_CONNECTIONS"))?;
+
+            let mut db_options = db::ConnectOptions::new(database_url);
+            db_options.max_connections(max_connections);
+            let db = LlmDatabase::new(db_options, executor.clone()).await?;
+
+            Some(Arc::new(db))
+        } else {
+            None
+        };
+
         let user_agent = format!("Zed Server/{}", env!("CARGO_PKG_VERSION"));
         let http_client = IsahcHttpClient::builder()
             .default_header("User-Agent", user_agent)
@@ -38,6 +60,7 @@ impl LlmState {
         let this = Self {
             config,
             executor,
+            db,
             http_client,
         };