feat(computed): allow computed get/set to have different types

[Alfred-Skyblue]

resolve #7271

In certain cases, we would like the computed property's getter and setter to have different types. This would provide added convenience in our usage, such as having the getter return a string while the setter accepts an object. In this PR, I have added a second generic parameter to the computed property to specify the type of the setter. With this enhancement, we can set different types for the getter and setter of computed using the following approach.

Examples:

const obj = ref({
  name: 'foo'
})

const newObj = computed<string, typeof obj.value>({
  get() {
    return JSON.stringify(obj.value)
  },
  set(val) {
    obj.value = val
  }
})
console.log(newObj.value) // string

newObj.value = { name: 'bar' } // object

[sxzz]

That's great! It's exactly what I wanted to do before. However, we need to explore ways to ensure compatibility with TS versions higher than 4.4. Perhaps we can use typeVersions to differentiate between TS >= 5.1 and other versions.

[Alfred-Skyblue]

That's great! It's exactly what I wanted to do before. However, we need to explore ways to ensure compatibility with TS versions higher than 4.4. Perhaps we can use typeVersions to differentiate between TS >= 5.1 and other versions.

If you use typeVersions to handle it, will it cause users to need to modify the tsconfig.json file in the project?

[sxzz]

No, it doesn't need to. The only thing that needs to be done is to add typesVersions in the package.json file of Vue.

https://www.typescriptlang.org/docs/handbook/declaration-files/publishing.html#version-selection-with-typesversions

[Alfred-Skyblue]

That's great, we can use typesVersions to differentiate versions less than 5.1.