Added create functions to allow batch processing

[Henk3000]

I was using this code to create a chatter post on a trigger and had a requirement to create a chatter post for each record and therefore I concluded that I needed to bulk insert the feed items.

As the current repo only allowed me to post individual feed items I altered it to "create" instead of directly posting a feed item.

my code now looks like this:

List<ConnectApi.BatchInput> batchInputs = new List<ConnectApi.BatchInput>();
for(Account acc : accs){
  String postMessage = 'test post message for {record:' + acc.Id + '}';
  ConnectApi.FeedItemInput input = ConnectApiHelper.createFeedItemWithRichText(acc.Id, postMessage);
  batchInputs.add(new ConnectApi.BatchInput(input));
}
ConnectApi.ChatterFeeds.postFeedElementBatch(null, batchInputs);

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