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/terminal_codegen.rs

@@ -1,7 +1,7 @@
 use crate::inline_prompt_editor::CodegenStatus;
 use client::telemetry::Telemetry;
 use futures::{channel::mpsc, SinkExt, StreamExt};
-use gpui::{AppContext, EventEmitter, Model, ModelContext, Task};
+use gpui::{App, Context, Entity, EventEmitter, Task};
 use language_model::{LanguageModelRegistry, LanguageModelRequest};
 use language_models::report_assistant_event;
 use std::{sync::Arc, time::Instant};
@@ -11,7 +11,7 @@ use terminal::Terminal;
 pub struct TerminalCodegen {
     pub status: CodegenStatus,
     pub telemetry: Option<Arc<Telemetry>>,
-    terminal: Model<Terminal>,
+    terminal: Entity<Terminal>,
     generation: Task<()>,
     pub message_id: Option<String>,
     transaction: Option<TerminalTransaction>,
@@ -20,7 +20,7 @@ pub struct TerminalCodegen {
 impl EventEmitter<CodegenEvent> for TerminalCodegen {}
 
 impl TerminalCodegen {
-    pub fn new(terminal: Model<Terminal>, telemetry: Option<Arc<Telemetry>>) -> Self {
+    pub fn new(terminal: Entity<Terminal>, telemetry: Option<Arc<Telemetry>>) -> Self {
         Self {
             terminal,
             telemetry,
@@ -31,7 +31,7 @@ impl TerminalCodegen {
         }
     }
 
-    pub fn start(&mut self, prompt: LanguageModelRequest, cx: &mut ModelContext<Self>) {
+    pub fn start(&mut self, prompt: LanguageModelRequest, cx: &mut Context<Self>) {
         let Some(model) = LanguageModelRegistry::read_global(cx).active_model() else {
             return;
         };
@@ -131,20 +131,20 @@ impl TerminalCodegen {
         cx.notify();
     }
 
-    pub fn stop(&mut self, cx: &mut ModelContext<Self>) {
+    pub fn stop(&mut self, cx: &mut Context<Self>) {
         self.status = CodegenStatus::Done;
         self.generation = Task::ready(());
         cx.emit(CodegenEvent::Finished);
         cx.notify();
     }
 
-    pub fn complete(&mut self, cx: &mut ModelContext<Self>) {
+    pub fn complete(&mut self, cx: &mut Context<Self>) {
         if let Some(transaction) = self.transaction.take() {
             transaction.complete(cx);
         }
     }
 
-    pub fn undo(&mut self, cx: &mut ModelContext<Self>) {
+    pub fn undo(&mut self, cx: &mut Context<Self>) {
         if let Some(transaction) = self.transaction.take() {
             transaction.undo(cx);
         }
@@ -160,27 +160,27 @@ pub const CLEAR_INPUT: &str = "\x15";
 const CARRIAGE_RETURN: &str = "\x0d";
 
 struct TerminalTransaction {
-    terminal: Model<Terminal>,
+    terminal: Entity<Terminal>,
 }
 
 impl TerminalTransaction {
-    pub fn start(terminal: Model<Terminal>) -> Self {
+    pub fn start(terminal: Entity<Terminal>) -> Self {
         Self { terminal }
     }
 
-    pub fn push(&mut self, hunk: String, cx: &mut AppContext) {
+    pub fn push(&mut self, hunk: String, cx: &mut App) {
         // Ensure that the assistant cannot accidentally execute commands that are streamed into the terminal
         let input = Self::sanitize_input(hunk);
         self.terminal
             .update(cx, |terminal, _| terminal.input(input));
     }
 
-    pub fn undo(&self, cx: &mut AppContext) {
+    pub fn undo(&self, cx: &mut App) {
         self.terminal
             .update(cx, |terminal, _| terminal.input(CLEAR_INPUT.to_string()));
     }
 
-    pub fn complete(&self, cx: &mut AppContext) {
+    pub fn complete(&self, cx: &mut App) {
         self.terminal.update(cx, |terminal, _| {
             terminal.input(CARRIAGE_RETURN.to_string())
         });