Uplift clippy::for_loops_over_fallibles lint into rustc

[WaffleLapkin]

This PR, as the title suggests, uplifts clippy::for_loops_over_fallibles lint into rustc. This lint warns for code like this:

for _ in Some(1) {}
for _ in Ok::<_, ()>(1) {}

i.e. directly iterating over Option and Result using for loop.

There are a number of suggestions that this PR adds (on top of what clippy suggested):

1. If the argument (? is there a better name for that expression) of a for loop is a .next() call, then we can suggest removing it (or rather replacing with .by_ref() to allow iterator being used later)

    for _ in iter.next() {}
    // turns into
    for _ in iter.by_ref() {}

2. (otherwise) We can suggest using while let, this is useful for non-iterator, iterator-like things like [async] channels

   for _ in rx.recv() {}
   // turns into
   while let Some(_) = rx.recv() {}

3. If the argument type is Result<impl IntoIterator, _> and the body has a Result<_, _> type, we can suggest using ?

   for _ in f() {}
   // turns into
   for _ in f()? {}

4. To preserve the original behavior and clear intent, we can suggest using if let

   for _ in f() {}
   // turns into
   if let Some(_) = f() {}

(P.S. Some and Ok are interchangeable depending on the type)

I still feel that the lint wording/look is somewhat off, so I'll be happy to hear suggestions (on how to improve suggestions :D)!

Resolves #99272