fix: better handling of SelfParam in assist 'inline_call'
fix#15470.
The current `inline_call` directly translates `&self` into `let ref this = ...;` and `&mut self` into `let ref mut this = ...;`. However, it does not handle some complex scenarios.
This PR addresses the following transformations (assuming the receiving object is `obj`):
- `self`: `let this = obj`
- `mut self`: `let mut this = obj`
- `&self`: `let this = &obj`
- `&mut self`
+ If `obj` is `let mut obj = ...`, use a mutable reference: `let this = &mut obj`
+ If `obj` is `let obj = &mut ...;`, perform a reborrow: `let this = &mut *obj`
f4fec4ff65