Isolated declarations: if class property type is inferred to literal, it should remain a value

```
export class A {
  readonly prop = 1
}
```

is currently transformed to
```
export declare class A {
  readonly prop: 1
}
```

but TSC emits
```
export declare class A {
  readonly prop = 1
}
```

https://github.com/oxc-project/oxc/pull/4027#discussion_r1662679027