feat: Unified as the key of raw in vue3

[edwardnyc]

We now use Vue Demi to work, such as using variables named at the beginning of $to skip the reactive.

I think we should keep the same raw key as vue3

https://github.com/vuejs/core/blob/4a3237ad9300693e465f82a6be3552565a1c4be3/packages/reactivity/src/reactive.ts#L17