toRefs not working correctly with writable computed refs

[wtykirby]

If you use toRefs with a writable computed the set method is never executed.

Here is an example:

import { ref, computed } from 'vue';
import { toRefs } from '@vueuse/core';

const x = ref({ bar: 'Bar' });

const foo = computed<{ bar: string }>({
  get() {
    return x.value;
  },
  set(v) {
    console.log('Setting value', v); // Never called
    x.value = v;
  }
});

const { bar } = toRefs(foo);
bar.value = 'Baz';

Although both bar and x will have their underlying values updated in this example, it does not go through the set method as expected. This prevents toRefs from being used with other methods that return writable computed refs like useVModel. In one of the example use cases with useVModel the "update:data" is never actually emitted like it shows.

If this sounds like a legitimate issue I would like to open a PR to resolve it.