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/ui/src/components/dropdown_menu.rs

@@ -1,5 +1,5 @@
 #![allow(missing_docs)]
-use gpui::{ClickEvent, Corner, CursorStyle, MouseButton, View};
+use gpui::{ClickEvent, Corner, CursorStyle, Entity, MouseButton};
 
 use crate::{prelude::*, ContextMenu, PopoverMenu};
 
@@ -7,7 +7,7 @@ use crate::{prelude::*, ContextMenu, PopoverMenu};
 pub struct DropdownMenu {
     id: ElementId,
     label: SharedString,
-    menu: View<ContextMenu>,
+    menu: Entity<ContextMenu>,
     full_width: bool,
     disabled: bool,
 }
@@ -16,7 +16,7 @@ impl DropdownMenu {
     pub fn new(
         id: impl Into<ElementId>,
         label: impl Into<SharedString>,
-        menu: View<ContextMenu>,
+        menu: Entity<ContextMenu>,
     ) -> Self {
         Self {
             id: id.into(),
@@ -41,10 +41,10 @@ impl Disableable for DropdownMenu {
 }
 
 impl RenderOnce for DropdownMenu {
-    fn render(self, _cx: &mut WindowContext) -> impl IntoElement {
+    fn render(self, _window: &mut Window, _cx: &mut App) -> impl IntoElement {
         PopoverMenu::new(self.id)
             .full_width(self.full_width)
-            .menu(move |_cx| Some(self.menu.clone()))
+            .menu(move |_window, _cx| Some(self.menu.clone()))
             .trigger(DropdownMenuTrigger::new(self.label).full_width(self.full_width))
             .attach(Corner::BottomLeft)
     }
@@ -57,7 +57,7 @@ struct DropdownMenuTrigger {
     selected: bool,
     disabled: bool,
     cursor_style: CursorStyle,
-    on_click: Option<Box<dyn Fn(&ClickEvent, &mut WindowContext) + 'static>>,
+    on_click: Option<Box<dyn Fn(&ClickEvent, &mut Window, &mut App) + 'static>>,
 }
 
 impl DropdownMenuTrigger {
@@ -93,7 +93,7 @@ impl Toggleable for DropdownMenuTrigger {
 }
 
 impl Clickable for DropdownMenuTrigger {
-    fn on_click(mut self, handler: impl Fn(&ClickEvent, &mut WindowContext) + 'static) -> Self {
+    fn on_click(mut self, handler: impl Fn(&ClickEvent, &mut Window, &mut App) + 'static) -> Self {
         self.on_click = Some(Box::new(handler));
         self
     }
@@ -105,7 +105,7 @@ impl Clickable for DropdownMenuTrigger {
 }
 
 impl RenderOnce for DropdownMenuTrigger {
-    fn render(self, cx: &mut WindowContext) -> impl IntoElement {
+    fn render(self, _window: &mut Window, cx: &mut App) -> impl IntoElement {
         let disabled = self.disabled;
 
         h_flex()
@@ -147,10 +147,10 @@ impl RenderOnce for DropdownMenuTrigger {
                     }),
             )
             .when_some(self.on_click.filter(|_| !disabled), |el, on_click| {
-                el.on_mouse_down(MouseButton::Left, |_, cx| cx.prevent_default())
-                    .on_click(move |event, cx| {
+                el.on_mouse_down(MouseButton::Left, |_, window, _| window.prevent_default())
+                    .on_click(move |event, window, cx| {
                         cx.stop_propagation();
-                        (on_click)(event, cx)
+                        (on_click)(event, window, cx)
                     })
             })
     }