Warn when attempting to block users which have advanced rights

[Dreamy-Jazz]

I used the tool on https://en.wikipedia.org/wiki/Wikipedia:Sockpuppet_investigations/That_guy_who_plays_games to block socks, but I had (without meaning to) ended up blocking a user mentioned in the report who has more than just extended confirmed rights.

I would like if the tool could specifically warn that I'm blocking a user who has more than just extended confirmed rights, as doing this intentionally is a rare occurrence and (such as in this case) is unintended.

[TheSandDoctor]

@Dreamy-Jazz what rights would you consider "advanced" for the purposes of this? Thankfully spiHelperIsAdmin does give a leaping off point for implementing this. If I had a list, I might even take a shot at opening a pull request for this but will need to brush up on this code base as I haven't touched it before.

That said, if anyone else wants to have at it...go ahead.

[Dreamy-Jazz]

I would probably consider "advanced" to be anyone who has more than extended confirmed rights.