keymap: Make F10 toggle the menu on Linux (#29607)

Closes: https://github.com/zed-industries/zed/issues/27271

Release Notes:

- Added support for F10 toggling menus on Linux

assets/keymaps/default-linux.json

@@ -520,6 +520,7 @@
       "shift-new": "workspace::NewWindow",
       "ctrl-shift-n": "workspace::NewWindow",
       "ctrl-`": "terminal_panel::ToggleFocus",
+      "f10": ["app_menu::OpenApplicationMenu", "Zed"],
       "alt-1": ["workspace::ActivatePane", 0],
       "alt-2": ["workspace::ActivatePane", 1],
       "alt-3": ["workspace::ActivatePane", 2],
@@ -578,6 +579,7 @@
   {
     "context": "ApplicationMenu",
     "bindings": {
+      "f10": "menu::Cancel",
       "left": "app_menu::ActivateMenuLeft",
       "right": "app_menu::ActivateMenuRight"
     }