Move UI code from assistant_context_editor -> agent_ui (#33289)

This breaks a transitive dependency of `agent` on UI crates. I've also
found and eliminated some dead code in assistant_context_editor.

Release Notes:

- N/A

crates/agent/Cargo.toml

@@ -21,7 +21,7 @@ test-support = [
 [dependencies]
 agent_settings.workspace = true
 anyhow.workspace = true
-assistant_context_editor.workspace = true
+assistant_context.workspace = true
 assistant_tool.workspace = true
 chrono.workspace = true
 client.workspace = true

crates/agent/src/context.rs

@@ -1,5 +1,5 @@
 use crate::thread::Thread;
-use assistant_context_editor::AssistantContext;
+use assistant_context::AssistantContext;
 use assistant_tool::outline;
 use collections::HashSet;
 use futures::future;

crates/agent/src/context_store.rs

@@ -8,7 +8,7 @@ use crate::{
     thread_store::ThreadStore,
 };
 use anyhow::{Context as _, Result, anyhow};
-use assistant_context_editor::AssistantContext;
+use assistant_context::AssistantContext;
 use collections::{HashSet, IndexSet};
 use futures::{self, FutureExt};
 use gpui::{App, Context, Entity, EventEmitter, Image, SharedString, Task, WeakEntity};

crates/agent/src/history_store.rs

@@ -3,7 +3,7 @@ use crate::{
     thread_store::{SerializedThreadMetadata, ThreadStore},
 };
 use anyhow::{Context as _, Result};
-use assistant_context_editor::SavedContextMetadata;
+use assistant_context::SavedContextMetadata;
 use chrono::{DateTime, Utc};
 use gpui::{App, AsyncApp, Entity, SharedString, Task, prelude::*};
 use itertools::Itertools;
@@ -62,7 +62,7 @@ enum SerializedRecentOpen {
 
 pub struct HistoryStore {
     thread_store: Entity<ThreadStore>,
-    context_store: Entity<assistant_context_editor::ContextStore>,
+    context_store: Entity<assistant_context::ContextStore>,
     recently_opened_entries: VecDeque<HistoryEntryId>,
     _subscriptions: Vec<gpui::Subscription>,
     _save_recently_opened_entries_task: Task<()>,
@@ -71,7 +71,7 @@ pub struct HistoryStore {
 impl HistoryStore {
     pub fn new(
         thread_store: Entity<ThreadStore>,
-        context_store: Entity<assistant_context_editor::ContextStore>,
+        context_store: Entity<assistant_context::ContextStore>,
         initial_recent_entries: impl IntoIterator<Item = HistoryEntryId>,
         cx: &mut Context<Self>,
     ) -> Self {

crates/agent/src/thread_store.rs

@@ -96,7 +96,7 @@ impl SharedProjectContext {
     }
 }
 
-pub type TextThreadStore = assistant_context_editor::ContextStore;
+pub type TextThreadStore = assistant_context::ContextStore;
 
 pub struct ThreadStore {
     project: Entity<Project>,