fix(reactivity): triggerRef working with toRef from reactive

[antfu]

triggerRef allows forcing update the ref created by ref and shallowRef, but not the one from toRef.

For example

const foo = ref(1)

watchEffect(() => {
  console.log('update foo', foo.value)
})

triggerRef(foo) // triggers

const state = reactive({ foo: 1 })
const foo = toRef(state, 'foo')


watchEffect(() => {
  console.log('update foo', foo.value)
})

triggerRef(foo) // does not triggers

It's because the ref created by toRef did not forward the .dep attribute. This PR fixes it.

Playground Before:

https://sfc.vuejs.org/#eNp9kU1ugzAQha8y8gaiEGi7RCRSr1B16Q2BISENtjU2tBLy3Ts2JU1bqRvwvHn+PD+zeDYmn0YUpahsQ71xYNGN5iBVPxhNDmYg7DL+1I3rJ8yg0YMZHbYZOOpPJ6SXkHc6/hR+uNe+eQMPHekBEmYnUknVaGWZ7WqHsL/R0hk6rUt4BL9ZPSywI/LS6M8gYS1hA8BqavSoXAR16cOPzLEm1tci03QD+wPMwRHv5FN9HRG226AQt0oqvLjIUoUypFq7uL/93WzKfrYFa1UsQ+NxceBwMFcumCOAqu2nAxdTwjzHoryviqDdkqNp2RzzSzveQ2rPery2cER42qz+qriRRSaWveyG2uQXqxVvLtYnvxJWCkYGJWg8/hBLcXbO2LIobNeEfV9srulU8CknfrofMEc77I6k3y0Sg6XI7hgFixPSjlC1SEj/MX9Z/3AD1vP4hP8EmTTcTA==

Playground After:

https://deploy-preview-7507--vue-sfc-playground.netlify.app/#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