Eliminate GPUI View, ViewContext, and WindowContext types (#22632)

There's still a bit more work to do on this, but this PR is compiling
(with warnings) after eliminating the key types. When the tasks below
are complete, this will be the new narrative for GPUI:

- `Entity<T>` - This replaces `View<T>`/`Model<T>`. It represents a unit
of state, and if `T` implements `Render`, then `Entity<T>` implements
`Element`.
- `&mut App` This replaces `AppContext` and represents the app.
- `&mut Context<T>` This replaces `ModelContext` and derefs to `App`. It
is provided by the framework when updating an entity.
- `&mut Window` Broken out of `&mut WindowContext` which no longer
exists. Every method that once took `&mut WindowContext` now takes `&mut
Window, &mut App` and every method that took `&mut ViewContext<T>` now
takes `&mut Window, &mut Context<T>`

Not pictured here are the two other failed attempts. It's been quite a
month!

Tasks:

- [x] Remove `View`, `ViewContext`, `WindowContext` and thread through
`Window`
- [x] [@cole-miller @mikayla-maki] Redraw window when entities change
- [x] [@cole-miller @mikayla-maki] Get examples and Zed running
- [x] [@cole-miller @mikayla-maki] Fix Zed rendering
- [x] [@mikayla-maki] Fix todo! macros and comments
- [x] Fix a bug where the editor would not be redrawn because of view
caching
- [x] remove publicness window.notify() and replace with
`AppContext::notify`
- [x] remove `observe_new_window_models`, replace with
`observe_new_models` with an optional window
- [x] Fix a bug where the project panel would not be redrawn because of
the wrong refresh() call being used
- [x] Fix the tests
- [x] Fix warnings by eliminating `Window` params or using `_`
- [x] Fix conflicts
- [x] Simplify generic code where possible
- [x] Rename types
- [ ] Update docs

### issues post merge

- [x] Issues switching between normal and insert mode
- [x] Assistant re-rendering failure
- [x] Vim test failures
- [x] Mac build issue



Release Notes:

- N/A

---------

Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Cole Miller <cole@zed.dev>
Co-authored-by: Mikayla <mikayla@zed.dev>
Co-authored-by: Joseph <joseph@zed.dev>
Co-authored-by: max <max@zed.dev>
Co-authored-by: Michael Sloan <michael@zed.dev>
Co-authored-by: Mikayla Maki <mikaylamaki@Mikaylas-MacBook-Pro.local>
Co-authored-by: Mikayla <mikayla.c.maki@gmail.com>
Co-authored-by: joão <joao@zed.dev>

crates/assistant2/src/thread.rs

@@ -6,7 +6,7 @@ use chrono::{DateTime, Utc};
 use collections::{BTreeMap, HashMap, HashSet};
 use futures::future::Shared;
 use futures::{FutureExt as _, StreamExt as _};
-use gpui::{AppContext, EventEmitter, ModelContext, SharedString, Task};
+use gpui::{App, Context, EventEmitter, SharedString, Task};
 use language_model::{
     LanguageModel, LanguageModelCompletionEvent, LanguageModelRegistry, LanguageModelRequest,
     LanguageModelRequestMessage, LanguageModelToolResult, LanguageModelToolUse,
@@ -76,7 +76,7 @@ pub struct Thread {
 }
 
 impl Thread {
-    pub fn new(tools: Arc<ToolWorkingSet>, _cx: &mut ModelContext<Self>) -> Self {
+    pub fn new(tools: Arc<ToolWorkingSet>, _cx: &mut Context<Self>) -> Self {
         Self {
             id: ThreadId::new(),
             updated_at: Utc::now(),
@@ -99,7 +99,7 @@ impl Thread {
         id: ThreadId,
         saved: SavedThread,
         tools: Arc<ToolWorkingSet>,
-        _cx: &mut ModelContext<Self>,
+        _cx: &mut Context<Self>,
     ) -> Self {
         let next_message_id = MessageId(saved.messages.len());
 
@@ -154,7 +154,7 @@ impl Thread {
         self.summary.clone().unwrap_or(DEFAULT)
     }
 
-    pub fn set_summary(&mut self, summary: impl Into<SharedString>, cx: &mut ModelContext<Self>) {
+    pub fn set_summary(&mut self, summary: impl Into<SharedString>, cx: &mut Context<Self>) {
         self.summary = Some(summary.into());
         cx.emit(ThreadEvent::SummaryChanged);
     }
@@ -194,7 +194,7 @@ impl Thread {
         &mut self,
         text: impl Into<String>,
         context: Vec<ContextSnapshot>,
-        cx: &mut ModelContext<Self>,
+        cx: &mut Context<Self>,
     ) {
         let message_id = self.insert_message(Role::User, text, cx);
         let context_ids = context.iter().map(|context| context.id).collect::<Vec<_>>();
@@ -207,7 +207,7 @@ impl Thread {
         &mut self,
         role: Role,
         text: impl Into<String>,
-        cx: &mut ModelContext<Self>,
+        cx: &mut Context<Self>,
     ) -> MessageId {
         let id = self.next_message_id.post_inc();
         self.messages.push(Message {
@@ -244,7 +244,7 @@ impl Thread {
     pub fn to_completion_request(
         &self,
         _request_kind: RequestKind,
-        _cx: &AppContext,
+        _cx: &App,
     ) -> LanguageModelRequest {
         let mut request = LanguageModelRequest {
             messages: vec![],
@@ -314,7 +314,7 @@ impl Thread {
         &mut self,
         request: LanguageModelRequest,
         model: Arc<dyn LanguageModel>,
-        cx: &mut ModelContext<Self>,
+        cx: &mut Context<Self>,
     ) {
         let pending_completion_id = post_inc(&mut self.completion_count);
 
@@ -439,7 +439,7 @@ impl Thread {
         });
     }
 
-    pub fn summarize(&mut self, cx: &mut ModelContext<Self>) {
+    pub fn summarize(&mut self, cx: &mut Context<Self>) {
         let Some(provider) = LanguageModelRegistry::read_global(cx).active_provider() else {
             return;
         };
@@ -497,7 +497,7 @@ impl Thread {
         assistant_message_id: MessageId,
         tool_use_id: LanguageModelToolUseId,
         output: Task<Result<String>>,
-        cx: &mut ModelContext<Self>,
+        cx: &mut Context<Self>,
     ) {
         let insert_output_task = cx.spawn(|thread, mut cx| {
             let tool_use_id = tool_use_id.clone();