feat: allow String as type of key

[Shinigami92]

This is a TypeScript only improvement
It allows to pass a special case like this:

<script setup lang="ts">
// import type { MyItem } from '@/shared/models/MyItem';
import { ref } from 'vue';

interface NodeId extends String {
//                       ^^^^^^ this is the important part for the reason of this PR
  _nodeIdBrand: string;
}

interface MyItemId extends NodeId {
  _myItemIdBrand: string;
}

interface MyItem extends BaseNode<MyItemId> {
  label: string;
}

const items = ref<MyItem[]>([/*...*/]);

function toAny(value: any): any {
  return value;
}
</script>

<template lang="pug">
ul
  //- Previously I needed this: li(v-for="item in items", :key="toAny(item.id)")
  li(v-for="item in items", :key="item.id")
    span {{ item.label }}
</template>

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[Shinigami92]

I'm unsure if the failing e2e is related to my changes 🤔
Could we try to rerun it?

[KaelWD]

#2633 - keys can basically be {}

[Shinigami92]

#2633 - keys can basically be {}

I saw that issue, but hoped that my can be merged earlier on the road to that

[KaelWD]

It already works at runtime, the types just need to be changed. {} would work for any object instead of having a special case just for String.

[Shinigami92]

Yeah I know, literally the first sentence in the PR description says that 😅
There is already another PR to solve the issue you are trying to explain
But this is not my issue and it seems like it doesn't get priority
So I opened this one to give at least a fix for my case
I do not use objects and I don't want to use objects as key as I think that is bad practice