fix: allow dependency.platforms.[platform] to be null again

[tido64]

Summary:

Resolves #1612.

Test Plan:

1. Clone and check out the branch with a repro:

   git clone https://github.com/microsoft/react-native-test-app.git
   cd react-native-test-app
   git checkout tido/enable-turbomodule
   

2. Apply below diff to make @react-native-community/cli think that react-native-test-app has native modules to link:

   diff --git a/android/app/src/turbomodule/java/com/microsoft/reacttestapp/turbomodule/TurboModuleManagerDelegate.kt b/android/app/src/turbomodule/java/com/microsoft/reacttestapp/turbomodule/TurboModuleManagerDelegate.kt
   index 2b02ad7..5ef4977 100644
   --- a/android/app/src/turbomodule/java/com/microsoft/reacttestapp/turbomodule/TurboModuleManagerDelegate.kt
   +++ b/android/app/src/turbomodule/java/com/microsoft/reacttestapp/turbomodule/TurboModuleManagerDelegate.kt
   @@ -20,7 +20,7 @@ typealias ReactTurboModuleManagerDelegate = ReactPackageTurboModuleManagerDelega
     */
    class TurboModuleManagerDelegate protected constructor(
        reactApplicationContext: ReactApplicationContext?,
   -    packages: PackagesList?
   +    packages: List<ReactPackage?>?
    ) : ReactTurboModuleManagerDelegate(reactApplicationContext, packages) {
   
        protected external fun initHybrid(): HybridData?

3. Run react-native config and note that the output contains both Android and iOS modules:

   cd example
   yarn react-native config
   

4. Disable autolinking for Android:

   diff --git a/react-native.config.js b/react-native.config.js
   index 833fe69..be3e6c5 100644
   --- a/react-native.config.js
   +++ b/react-native.config.js
   @@ -102,6 +102,7 @@ module.exports = {
      ],
      dependency: {
        platforms: {
   +      android: null,
          windows: null,
        },
      },

5. Run react-native config and verify that the output only contains iOS modules
6. Disable autolinking for iOS:

   diff --git a/react-native.config.js b/react-native.config.js
   index 833fe69..be3e6c5 100644
   --- a/react-native.config.js
   +++ b/react-native.config.js
   @@ -102,6 +102,7 @@ module.exports = {
      ],
      dependency: {
        platforms: {
   -      android: null,
   +      ios: null,
          windows: null,
        },
      },

7. Run react-native config and verify that the output only contains Android modules
8. Disable autolinking for both Android and iOS:

   diff --git a/react-native.config.js b/react-native.config.js
   index 833fe69..be3e6c5 100644
   --- a/react-native.config.js
   +++ b/react-native.config.js
   @@ -102,6 +102,7 @@ module.exports = {
      ],
      dependency: {
        platforms: {
   +      android: null,
          ios: null,
          windows: null,
        },
      },

9. Run react-native config and verify that the output contains no native modules

[thymikee]

Released in 8.0.2