[FIX] Threads and Discussions fixes

[ggazzo]

readded threads follow and unfollow Closes #14344
Allow change discussions properties #14027
fix edited messages for nrr disabled
should close #14158

[rodrigok]

@ggazzo can you split this in multiple PRs?

[ggazzo]

do you really think we need create 4 prs for 1020 lines, they are small fixes? I'm used to reviewing 4080 files and usually its not a big deal...if you really think it worth, sure I can I'm perfectly able to do :x

[rodrigok]

@ggazzo it's not due to the code changes, but the description of the changes, you are adding 4 fixes in a single change line in change log that means almost nothing. Would be much better if we have each of them listed in change logs and well described don't you think?

[ggazzo]

I really dont think it worth in that specific case or I would create separated prs on the beginning. but as you wish:
#14387
#14389
#14390
#14391
#14394
#14393