Merge #9773

9773: internal: Improve `extract_function` assist r=Veykril a=Veykril

- fix: It doesn't try to overwrite parts of selected comments any longer
- fix: It doesn't wrap tail expressions and return types in a result or option unnecessarily
- feat?: It now adds a `const` modifier to the created function if extract somethings from a const context 

Fixes #7840

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

Author: bors[bot]