fix: declare support for visionOS (#3024)

## Summary:

Properly declare support for visionOS. Without it, users will have to
[configure it
manually](https://github.com/microsoft/react-native-test-app/pull/2850/changes#diff-b026099318e278b777d6ecfb1168201bf77e1027b0c2e02ea67e7be0fa14fa8c).

Also fixes `platforms.macos.dependencyConfig` containing _project_
config instead of _dependency_.

This needs a backport to 0.81.

## Test Plan:

`react-native config` should output `visionos` fields:

```sh
% yarn react-native config
{
  ...
  "platforms": {
    "ios": {},
    "android": {},
    "macos": {
      "npmPackageName": "react-native-macos"
    },
    "visionos": {
      "npmPackageName": "react-native-macos"
    }
  },
  "assets": [],
  "project": {
    "ios": { ... },
    "android": { ... },
    "macos": null,
    "visionos": {
      "sourceDir": "/~/packages/example-visionos/visionos",
      "xcodeProject": {
        "name": "Example.xcworkspace",
        "path": ".",
        "isWorkspace": true
      },
      "assets": []
    }
  }
}
```