Add default keybinding cmd+backspace=esc:w for macOS (#3679)

regarding https://github.com/ghostty-org/ghostty/issues/3646

src/config/Config.zig

@@ -2577,6 +2577,11 @@ pub fn default(alloc_gpa: Allocator) Allocator.Error!Config {
             .{ .key = .{ .translated = .left }, .mods = .{ .super = true } },
             .{ .text = "\\x01" },
         );
+        try result.keybind.set.put(
+            alloc,
+            .{ .key = .{ .translated = .backspace }, .mods = .{ .super = true } },
+            .{ .esc = "\x15" },
+        );
         try result.keybind.set.put(
             alloc,
             .{ .key = .{ .translated = .left }, .mods = .{ .alt = true } },