Add suggestions for potentially misspelled #[derive] traits

[elliotekj]

I ran into an error when compiling a program a couple of days ago that turned out to be due to a spelling mistake. It was suggested by @carols10cents that I create an issue here to discuss adding a “Did you mean X?” hint when compiling fails because of a trait's name.

For clarity's sake, the screenshot below was the error I got and this is the sort of thing I'm suggesting:

error: Custom traits have been depreciated.
 --> src/main.rs:1:10
  |
1 | #[derive(debug)]
  |          ^^^^^
note: Did you mean `#[derive(Debug)]`?

I expect this hinges somewhat on whether or not #29644 goes through.

[jseyfried]

cc @keeperofdakeys

[keeperofdakeys]

By the way, I'm currently working on fixing this.

[petrochenkov]

cc #30197 (comment)