This PR fixes an issue with the `significant_drop_in_scrutinee`, where
the lint generates invalid Rust syntax when suggesting fixes for match
expressions that are part of larger expressions, such as in assignment
contexts. For example:
```rust
let mutex = Mutex::new(State {});
let _ = match mutex.lock().unwrap().foo() {
true => 0,
false => 1,
};
```
would suggest:
```rust
let _ = let value = mutex.lock().unwrap().foo();
match value {
```
With this PR, it now suggests:
```rust
let value = mutex.lock().unwrap().foo();
let _ = match value {
```
closes: #13986
changelog: [`significant_drop_in_scrutinee`] Fix incorrect suggestion
for `significant_drop_in_scrutinee` lint in expression context
d1b5fa2416