[Board] Add authed endpoint to create a Thread

[Xazin]

We will need an endpoint to create threads, the endpoint must require authentication.

The endpoint will take (and of course have the user from the token):

• Forum ID (Where to post the thread)
• Prefix ID (Optional)
• Subject
• Message

The task also includes creating a command CreateThreadCommand, that will require these validations:

1. Validate the user can create threads in the forum (fetch forum permission based on forumId and the users role)

The command should take the information received through the endpoint as arguments, and also require a User!

We will add support for creating polls etc. at a later point.