Do not use question as label

We don't want to have questions in the diagnostic output. Instead, we use wording that communicates uncertainty, like "might":

```
error[E0432]: unresolved import `spam`
  --> $DIR/import-from-missing-star-3.rs:2:9
   |
LL |     use spam::*;
   |         ^^^^ you might be missing crate `spam`
   |
   = help: consider adding `extern crate spam` to use the `spam` crate
```

tests/rustdoc-ui/issues/issue-61732.rs

@@ -1,4 +1,4 @@
 // This previously triggered an ICE.
 
 pub(in crate::r#mod) fn main() {}
-//~^ ERROR failed to resolve: maybe a missing crate `r#mod`
+//~^ ERROR failed to resolve: you might be missing crate `r#mod`