Use trait name instead of full constraint in suggestion message
```
help: consider restricting type parameter `T` with traits `Copy` and `Trait`
|
LL | fn duplicate_custom<T: Copy + Trait>(t: S<T>) -> (S<T>, S<T>) {
| ++++++++++++++
```
```
help: consider restricting type parameter `V` with trait `Copy`
|
LL | fn index<'a, K, V: std::marker::Copy>(map: &'a HashMap<K, V>, k: K) -> &'a V {
| +++++++++++++++++++
```