needless_borrows_for_generic_args: Handle when field operand impl Drop
Before this fix, the lint had a false positive, namely when a reference was taken to a field when the field operand implements a custom Drop. The compiler will refuse to partially move a type that implements Drop, because that would put the type in a weird state.
## False Positive Example (Fixed)
```rs
struct CustomDrop(String);
impl Drop for CustomDrop {
fn drop(&mut self) {}
}
fn check_str<P: AsRef<str>>(_to: P) {}
fn test() {
let owner = CustomDrop(String::default());
check_str(&owner.0); // Don't lint. `owner` can't be partially moved because it impl Drop
}
```
changelog: [`needless_borrows_for_generic_args`]: Handle when field operand impl Drop
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