(feat): Rate limits for spam comments

Summary

problem: mass identical comments on multiple posts from the same user

Steps to reproduce

comment the same thing multiple times on multiple posts

Platform information

all

What is the current bug behavior?

channels are allowed to mass post identical comments

What is the expected correct behavior?

Rate limit of 3 identical comments allowed in a row per channel, across the siteScreenshot__85_

Relevant logs and/or screenshots

(Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's very hard to read otherwise.)

Possible fixes

Rate limit of 3 identical comments allowed in a row per channel, across the site (this is the same as the Dissenter add on)