Auto merge of #94584 - pnkfelix:inject-use-suggestion-sites, r=ekuber

Auto merge of #94584 - pnkfelix:inject-use-suggestion-sites, r=ekuber

More robust fallback for `use` suggestion

Our old way to suggest where to add `use`s would first look for pre-existing `use`s in the relevant crate/module, and if there are *no* uses, it would fallback on trying to use another item as the basis for the suggestion.

But this was fragile, as illustrated in issue #87613

This PR instead identifies span of the first token after any inner attributes, and uses *that* as the fallback for the `use` suggestion.

Fix #87613