feat: get react-native package name from package.json in codegen script

[okwasniewski]

Summary:

This PR fixes the retrieval of react native package name to retrieve it from package.json.

This fixes the annoying message in codegen that poped up when installing pods:

[Codegen] Found react-native-macos
[Codegen] CodegenConfig Deprecated Setup for react-native-macos.
    The configuration file still contains the codegen in the libraries array.
    If possible, replace it with a single object.
  
BEFORE:
    {
      // ...
      "codegenConfig": {
        "libraries": [
          {
            "name": "libName1",
            "type": "all|components|modules",
            "jsSrcsRoot": "libName1/js"
          },
          {
            "name": "libName2",
            "type": "all|components|modules",
            "jsSrcsRoot": "libName2/src"
          }
        ]
      }
    }

    AFTER:
    {
      "codegenConfig": {
        "name": "libraries",
        "type": "all",
        "jsSrcsRoot": "."
      }
    }

Changelog:

[GENERAL] [CHANGED] - get react-native package name from package.json in codegen script

Test Plan:

Install pods

[facebook-github-bot]

@arushikesarwani94 has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@arushikesarwani94 merged this pull request in 65575e8.

[react-native-bot]

This pull request was successfully merged by @okwasniewski in 65575e8

^{When will my fix make it into a release? | How to file a pick request?}