Plugin hook for message_delete and message_move

[JE4GLE]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have searched for plugins that provide already provide the feature

Proposal

A plugin hook, which allows to get notified on message_delete and message_mvoe

Motivation and context

I want to write a plugin, which logs these actions for legal reasons.

[alecpl]

I'm not sure an IMAP client is the proper tool for that, I think such things should be done on the IMAP server.

That being said, we have already 'message_saved' hook, so adding 'message_delete' and 'message_move' could be added too, I suppose. Provide a pull request, please.

[alecpl]

Done.