Nuke GLFW, make zig build run on macOS build the Xcode project (#7815)

This PR does two things.

1. Build system improvements to make developing on macOS more enjoyable 
2. Delete the GLFW apprt

## Build System Improvements (macOS)

On macOS, there are a few major improvements:

* `zig build` now produces a full macOS app bundle and copies it into
`zig-out`
* `zig build run` now builds the macOS app and runs it, streaming logs
directly into the terminal
* `-Demit-macos-app` can control whether app bundle is created
* `-Dxcframework-target` can be set to one of `native` or `universal` to
control whether the xcframework uses only your target machines arch or
creates a universal one with macOS and iOS. This defaults to `native`
for the `run` command and `universal` for all others.
* The general flow of the `build.zig` file was improved to be more
declarative

## Nuke GLFW

> This deletes the GLFW apprt from the Ghostty codebase.
> 
> The GLFW apprt was the original apprt used by Ghostty (well, before
> Ghostty even had the concept of an "apprt" -- it was all just a single
> application then). It let me iterate on the core terminal features,
> rendering, etc. without bothering about the UI. It was a good way to
get
> started. But it has long since outlived its usefulness.
> 
> We've had a stable GTK apprt for Linux (and Windows via WSL) and a
> native macOS app via libghostty for awhile now. The GLFW apprt only
> remained within the tree for a few reasons:
> 
>   1. Primarily, it provided a faster feedback loop on macOS because
>      building the macOS app historically required us to hop out of the
>      zig build system and into Xcode, which is slow and cumbersome.
> 
>   2. It was a convenient way to narrow whether a bug was in the
> core Ghostty codebase or in the apprt itself. If a bug was in both
>      the glfw and macOS app then it was likely in the core.
> 
>   3. It provided us a way on macOS to test OpenGL.
> 
> All of these reasons are no longer valid. Respectively:
> 
> 1. Our Zig build scripts now execute the `xcodebuild` CLI directly and
>      can open the resulting app, stream logs, etc. This is the same
> experience we have on Linux. (Xcode has always been a dependency of
>      building on macOS in general, so this is not cumbersome.)
> 
>   2. We have a healthy group of maintainers, many of which have access
>      to both macOS and Linux, so we can quickly narrow down bugs
>      regardless of the apprt.
> 
> 3. Our OpenGL renderer hasn't been compatible with macOS for some time
>      now, so this is no longer a useful feature.
> 
> At this point, the GLFW apprt is just a burden. It adds complexity
> across the board, and some people try to run Ghostty with it in the
real
> world and get confused when it doesn't work (it's always been lacking
in
> features and buggy compared to the other apprts).
> 
> So, it's time to say goodbye. Its bittersweet because it is a big part
> of Ghostty's history, but we've grown up now and it's time to move on.
> Thank you, goodbye.
> 
> (NOTE: If you are a user of the GLFW apprt, then please fork the
project
> prior to this commit or start a new project based on it. We've warned
> against using it for a very, very long time now.)

src/renderer/generic.zig

@@ -1,6 +1,5 @@
 const std = @import("std");
 const builtin = @import("builtin");
-const glfw = @import("glfw");
 const xev = @import("xev");
 const wuffs = @import("wuffs");
 const apprt = @import("../apprt.zig");
@@ -606,20 +605,6 @@ pub fn Renderer(comptime GraphicsAPI: type) type {
             }
         };
 
-        /// Returns the hints that we want for this window.
-        pub fn glfwWindowHints(config: *const configpkg.Config) glfw.Window.Hints {
-            // If our graphics API provides hints, use them,
-            // otherwise fall back to generic hints.
-            if (@hasDecl(GraphicsAPI, "glfwWindowHints")) {
-                return GraphicsAPI.glfwWindowHints(config);
-            }
-
-            return .{
-                .client_api = .no_api,
-                .transparent_framebuffer = config.@"background-opacity" < 1,
-            };
-        }
-
         pub fn init(alloc: Allocator, options: renderer.Options) !Self {
             // Initialize our graphics API wrapper, this will prepare the
             // surface provided by the apprt and set up any API-specific