Allow method properties to be server functions (#72969)
With this PR, we are now allowing `"use server"` and `"use cache"` to be
used in method properties, e.g.:
```js
export const obj = {
async foo() {
'use cache'
return Math.random()
},
async bar() {
'use server'
console.log(42)
},
}
```
Or, more realistically, something like this:
```js
export const api = {
product: {
async fetch() {
'use cache'
return fetch('https://example.com').then((res) => res.json())
},
},
}
```
Supporting this pattern is mostly done for convenience; it allows users
to group server functions into a common object, using method properties.
Notably, we will not support the usage of `this` and `super`, for which
we will add build errors in a follow-up PR.
