Reply limit per submission

[kevinlul]

Bastion replies to comments and mentions a limited number of times per submission to prevent abuse, resetting when rebooted. This is not ideal for megathreads but is necessary to prevent more complex looping and abuse.

This limit could be enforced per top-level comment instead, but finding the top-level comment for a deeply-nested comment may be quite expensive: https://praw.readthedocs.io/en/stable/code_overview/models/comment.html#praw.models.Comment.parent
Could also consider ignoring deeply-nested comments if enforcing limit by top-level comment.

This is an open issue for what the limit should be (currently 10) or if alternative approaches are sufficient to prevent abuse.