[Feature] DM a Welcome Message to New Users

[DukeOfEtiquette]

When a new user enters the server, PM the user with the rules and how to assign themselves a role. Then change server permissions so white names cane only chat in #main until they assign themselves a role.

[ctsstc]

Looks like this was handled with @JWTappert changes on 5c04ded

Although it handles the title of this story, it doesn't meet the acceptance criteria of @DukeOfEtiquette story from what I can abstract.

Found this old closed issue: #43 so maybe I thought this was a duplicate but is different.

Assumed Acceptance Criteria

• User gets a DM about server rules from hackbot

Additional Acceptance Criteria

I assume this could be split into another story and added as a dependency to this story.

• Users start with white names
• White names are limited to #main channel
• Users can assign themselves roles
• Assigned roles give additional access

I'm not sure if Discord allows self-assigning roles (I thought it might now - depends on permissions) or if this would be new hackbot functionality? Most if not all of the acceptance criteria below needs to be handled with Discord server permissions. With this change though we should consider the usability changes that come with this: users will have to get over a hurdle before they can get to the channel they want. I'm not sure if we want to impose that on our users. We could still DM a message about assigning a role and allow users to assign themselves a role.

[ctsstc]

I've updated the title of the issue to better reflect the acceptance of the bot DM'ing a user a welcome message.