(feat): Only allow one top level comment unless subbed

Summary

Only allow one top level comment unless subbed

Steps to reproduce

(How one can reproduce the issue - this is very important)

Platform information

all

What is the current bug behavior?

anyone can comment as much and wherever they like

What is the expected correct behavior?

Only allow one top level comment unless subbed subbed users should be free to comment on each others posts un-subbed users should only be allowed one top level comment

THIS SOULD BE OPT-IN

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

(If you can, link to the line of code that might be responsible for the problem)