add a lint for find_map

[Eh2406]

There are a bunch of iterator chains that are clearer with the new find_map. Off the top of my head, .find(_).map(_) and .filter_map(_).nex(). I think clippy should have a lit for this like the filter_map and filter_next lints.

[basil-cow]

@flip1995 this one is long implemented too. (Also, should I always tag you in those issues or there are more appropriate channels?)

[flip1995]

Thanks! For Clippy I get notified for every comment/PR/issue/... anyway. Doesn't matter if I'm tagged or not.

I first look at the notifications I'm mentioned in though (if the list is long). Since these kind of issues are low hanging fruits, because I just have to click on close and give you a ❤️ for triage-ing, you can keep tagging me 👍