Auto merge of rust-lang#16846 - roife:fix-issue16826, r=Veykril

fix: incorrect handling of `use` and panic issue in `extract_module`.

fix rust-lang#16826

This PR includes the following changes:

1. Simplify the implementation partially, removing many unnecessary loops and `clone()`.

2. When it is found that the top level of the selection contains a `use` statement, a copy of the `use` will be reinserted before extraction. (rust-lang#16826)

3. Fixed an issue during `extract_module`, where if the top level of the selected part contains `A` and `use A::B`, it caused a duplication of `use A`.

Author: bors