Document User Security Buffer (Initial Moderation)

## Is your feature request related to a problem?
In a successful community, there is a line when the community begins to see new members coming in and creating spam posts in various ways. They get very creative too. They might post as much as a dozen times to get their spam content published, and might even masquerade as a well-intentioned member, only to later edit their seemingly harmless post to something else.

Spam comes in many forms too... It's not only backlinks we need to worry about. These links could lead to hacker-led websites that could legitimately damage someone's computer/phone in some way.

This can also be necessary for other reasons... Such as a new member instantly and repeatedly breaking the community's code of conduct before a moderator can catch it.

In either case, these are use cases that can and are detrimental to the well-being and growth of a community.

## Describe the solution you'd like
We already have flood control in place, but we need a buffer that can be uniquely configured in various communities to gently allow new members to join and participate. In short, we need the following settings in the forum.

- Scope: Global to all forums in a single module instance.
- Setting: New Posts Require Moderator Approval Until After ___ Posts Approved by a Moderator
- Setting: Unable to edit posts until ___ approved posts
- Setting: Unable to delete posts until ___ approved posts

## Describe alternatives you've considered
We have several other things that help to prevent the root issues we're trying to solve, but this is a critical one that doesn't yet exist.

## Additional context
Issue #109