Please add `implements` entry to federated platform packages

[loic-sharma]

Flutter-Tizen version
N/A

Plugin version
N/A

Describe the issue
Users cannot discover Tizen's federated platform packages on pub.dev using the implements-federated-plugin: syntax.

Federated platform packages, like url_launcher_tizen, should use the implements entry to indicate which app-facing package it implements. For example:

flutter:
  plugin:
    implements: url_launcher
    platforms:
      tizen:
        dartPluginClass: UrlLauncherPlugin

Docs: https://docs.flutter.dev/packages-and-plugins/developing-packages#federated-platform-packages

To reproduce

1. Navigate to: https://pub.dev/packages/url_launcher
2. Under the "More" section in the sidebar, press the "Packages that implement url_launcher" link
3. Check if url_launcher_tizen is listed in the results.

Log message
N/A

[JSUYA]

@loic-sharma
Thank you for the good advice!!. I proceeded with adding implements to the Tizen plugins. #1097