Export the MenuContext Injection Key

[aronduby]

I have a custom component that when it's within a Menu should use a MenuButton, but an XButton otherwise. I'd seen the error when MenuButton is included without being in a Menu so I looked into how it did that and saw it's using a provide/inject, but unfortunately it's using a symbol which isn't exported so I can't use in within the project.

headlessui/packages/@headlessui-vue/src/components/menu/menu.ts

Line 76 in d71fb9c

let MenuContext = Symbol('MenuContext') as InjectionKey<StateDefinition>