Resolves #3654 Moderation Tools Improvements

[effone]

Attempt to resolve #3654

[euantorano]

This looks good so far, just one minor nitpick and a comment for myself.

[Eldenroot]

@effone - please can you look at this and finish this one?

[effone]

This is done for now.
I think I have completed all the to-dos of this PR. If I have left something I will address separately.

[euantorano]

Some minor comments, mostly code style. I haven't tested this yet, just read the changes.

[effone]

All comments addressed.

[Ben-MyBB]

@effone - please can you look at this and finish this one?

Please can you review this?

[Eldenroot]

I applied to my board, at the first look and testing no problems so far.

[yuliu]

Current PHP code doesn't prevent users having relevant permissions from making a reply to a soft-deleted thread

[yuliu]

Anyone who wants to test this PR in an upgrades board for an existing one, please apply #3800.

Had some tests with issues mentioned in #3654 and it looks to me that all the issues have been addressed. However, I have some further questions:

• Thread Split is enabled even if there is only one post. I think this improvement could be applied to inline post mod tools as well for Merge posts, Split posts and Move posts. It doesn't matter if it's not changed.

[effone]

This is long pending @mybb/developers

[euantorano]

Thanks for the nudge @effone. I'll review it this week and merge.

[Eldenroot]

@euantorano - any feedback from testing?

[Eldenroot]

5 years later :) still a good improvement