Add support for private messages

[Naraujo13]

What does this pull request aim to achieve? 💯

Adds support to private messages

What this PR does?

• Adds collection threads to store conversations
• Updates the scripts, docs, and GitHub page
• Adds collection messages to store the conversation's messages

Feature

Desktop

Mobile

Collections

The following collections were modified:

Threads

Messages

[Naraujo13]

@joshmorel I don't know Luis' or Kevin's username here, so please add then as reviewers also 😅

[lmpeixoto]

@Naraujo13 I think you've done a great job. The only thing I'd change is the location, as @joshmorel said. Don't know if you'd like to add something about that?!

[Naraujo13]

@Naraujo13 I think you've done a great job. The only thing I'd change is the location, as @joshmorel said. Don't know if you'd like to add something about that?!

As mentioned in the model PR, I agree about removing the location ref.

I'm also questioning the need for an embedded ref for the author at all in the messages collection since that will always be used with a thread that already has it. Removing that might save us space and all the sync hassle.
What do you guys think?