Add a few more testing features (#36778)

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>

Procfile.web

@@ -0,0 +1,2 @@
+postgrest_llm: postgrest crates/collab/postgrest_llm.conf
+website: cd ../zed.dev; npm run dev -- --port=3000

crates/client/src/client.rs

@@ -66,6 +66,8 @@ pub static IMPERSONATE_LOGIN: LazyLock<Option<String>> = LazyLock::new(|| {
         .and_then(|s| if s.is_empty() { None } else { Some(s) })
 });
 
+pub static USE_WEB_LOGIN: LazyLock<bool> = LazyLock::new(|| std::env::var("ZED_WEB_LOGIN").is_ok());
+
 pub static ADMIN_API_TOKEN: LazyLock<Option<String>> = LazyLock::new(|| {
     std::env::var("ZED_ADMIN_API_TOKEN")
         .ok()
@@ -1392,12 +1394,14 @@ impl Client {
                     if let Some((login, token)) =
                         IMPERSONATE_LOGIN.as_ref().zip(ADMIN_API_TOKEN.as_ref())
                     {
+                        if !*USE_WEB_LOGIN {
                             eprintln!("authenticate as admin {login}, {token}");
 
                             return this
                                 .authenticate_as_admin(http, login.clone(), token.clone())
                                 .await;
                         }
+                    }
 
                     // Start an HTTP server to receive the redirect from Zed's sign-in page.
                     let server =