Added convenient toIdMessageRecipient method

[marceloverdijk]

@nbartels I don't know if you like this PR as it might mix some concerns (webhook/sendapi).
So I can understand if you reject it.
But if accepted it gives a easier api to use a sugar syntax to use the MessagingParticipant sender as input for the send api.

[nbartels]

@marceloverdijk can you explain why this is useful. I don't see it ATM, because the new method is a renamed "clone" method :)

[marceloverdijk]

Instead of

MessagingItem item = ..
MessagingParticipant sender = item.getSender();
IdMessageRecipient recipient = new IdMessageRecipient(sender.getId());

I could do something like:

MessagingItem item = ..
MessagingParticipant sender = item.getSender();
IdMessageRecipient recipient = sender.toIdMessageRecipient()

This gives a shorter/easier notation (without passing in the id manually) to create a recipient.

[nbartels]

Okay, I see. Let me think about it ...

[marceloverdijk]

No worries if you don't want to add it.
It would be my personal preference, but I also see the reasoning for not adding it.