Field shorthand overwritten in promote local to const assist
Currently, running `promote_local_to_const` on the following:
```rust
struct Foo {
bar: usize,
}
fn main() {
let $0bar = 0;
let foo = Foo { bar };
}
```
Results in:
```rust
struct Foo {
bar: usize,
}
fn main() {
const BAR: usize = 0;
let foo = Foo { BAR };
}
```
But instead should be something like:
```rust
struct Foo {
bar: usize,
}
fn main() {
const BAR: usize = 0;
let foo = Foo { bar: BAR };
}
```