Feature: Modify SendMessage function to take a models.Message parameter instead of a string

[ZakiChammaa]

Hi!

The function SendMessage(channel *models.Channel, text string) in realtime/messages.go currently takes a string and creates a models.Message variable in the function before sending it. This really limits what we can send to rocket.chat (we need to send attachments with the message for example).

I propose the following:

• Implement a feature to modify this function so that it takes a models.Message parameter instead of a string.
• Implement a new function called NewMessage(channel *models.Channel, text string) in realtime/messages.go that returns a basic message with a RoomID, a Msg, and an ID based on the function newRandomId().

Please let me know what you think about each of the above points. I can start working on a PR as soon as you approve these propositions.

Thanks!

[debdutdeb]

This issue can be closed now.