Remove dev_dependencys from generated plugin registrants on all platforms #161348
Description
#161343 will remove dev dependencies from the generated plugin registrant for Android as part of a fix for enabling dev dependncies being removed from release builds (#160407).
We should follow up that PR by doing the same for all platforms, just not Android. This is what the change for Android looked like for context:
Future<void> _writeAndroidPluginRegistrant(FlutterProject project, List<Plugin> plugins, {required bool releaseMode}) async {
Iterable<Plugin> methodChannelPlugins = _filterMethodChannelPlugins(plugins, AndroidPlugin.kConfigKey);
if (releaseMode) {
methodChannelPlugins = methodChannelPlugins.where((Plugin p) => !p.isDevDependency);
}