Start separating authentication from connection to collab (#35471)

This pull request should be idempotent, but lays the groundwork for
avoiding to connect to collab in order to interact with AI features
provided by Zed.

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>
Co-authored-by: Richard Feldman <oss@rtfeldman.com>

crates/language_model/src/model/cloud_model.rs

@@ -3,10 +3,11 @@ use std::sync::Arc;
 
 use anyhow::Result;
 use client::Client;
+use cloud_llm_client::Plan;
 use gpui::{
     App, AppContext as _, AsyncApp, Context, Entity, EventEmitter, Global, ReadGlobal as _,
 };
-use proto::{Plan, TypedEnvelope};
+use proto::TypedEnvelope;
 use smol::lock::{RwLock, RwLockUpgradableReadGuard, RwLockWriteGuard};
 use thiserror::Error;
 
@@ -30,7 +31,7 @@ pub struct ModelRequestLimitReachedError {
 impl fmt::Display for ModelRequestLimitReachedError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let message = match self.plan {
-            Plan::Free => "Model request limit reached. Upgrade to Zed Pro for more requests.",
+            Plan::ZedFree => "Model request limit reached. Upgrade to Zed Pro for more requests.",
             Plan::ZedPro => {
                 "Model request limit reached. Upgrade to usage-based billing for more requests."
             }