fix: declare support for visionOS

[tido64]

Summary:

Properly declare support for visionOS. Without it, users will have to configure it manually.

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:

% 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": []
    }
  }
}