Rollup merge of #107553 - edward-shen:edward-shen/suggest-null-ptr, r=WaffleLapkin

Suggest std::ptr::null if literal 0 is given to a raw pointer function argument

Implementation feels a little sus (we're parsing the span for a `0`) but it seems to fall in line the string-expected-found-char condition right above this check, so I think it's fine.

Feedback appreciated on help text? I think it's consistent but it does sound a little awkward maybe?

Fixes #107517